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# /sci/ - Science & Math

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Formerly >>11100698
Why the hell did you lads actually wait for me edition.

 >> Anonymous Tue Nov 5 20:11:00 2019 No.11120914   I was tempted to start one. Didn't know if you'd mind~
 >> Anonymous Tue Nov 5 20:37:43 2019 No.11120997 File: 138 KB, 712x1104, IMG_1426.jpg [View same] [iqdb] [saucenao] [google] [report] Asking again but more specific now to see if I get an answer this time.You guys know what the symbol below the valve means (it's a P&ID diagram btw)? It looks like a check valve but I also have the irl photos of the sistem and I don't see anything there.
 >> Anonymous Tue Nov 5 20:38:29 2019 No.11121001 File: 272 KB, 604x900, __patchouli_knowledge_touhou_drawn_by_maguro_mawaru_sushi__afae8c03397e57bd75620bca28eb7a72.png [View same] [iqdb] [saucenao] [google] [report] Is there any archive that pops up a posting window like 4chan does? I had to actually tally this shit up by copying and pasting to notepad.There are probably some formatting errors, but catching them without just posting would be a huge pain.>>11120914I obviously wouldn't.Unanswered questions from the previous thread:Maths questions:>>11103791>>11107185>>11109144 [I still need those recs.]>>11110657Physics questions:>>11101366>>11103628>>11105934>>11114845>>11118274Chemistry questions:>>11102551>>11107578Biology questions:>>11113959>>11115393/g/ questions:>>11114863 [Quantum computing.]Stupid questions:>>11102675 [I have absolutely no idea where this goes.]>>11103669>>11111002>>11113761>>11113952>>11114501>>11117485>>11117796>>1119639>>11119653>>11119814
 >> Anonymous Tue Nov 5 20:40:27 2019 No.11121009 How can blood pressure medicines work without just killing you? Doesn't the body only increase the pressure in its veins when it NEEDS that pressure to be higher?
 >> Anonymous Tue Nov 5 20:56:06 2019 No.11121054 >>11121009I imagine they can be continuously elevated beyond the point it's considered healthy due to stress, bad diet, etc. My father regularly reports +180/+120 when he's had a morning where things didn't exactly go his way.
 >> Anonymous Tue Nov 5 20:56:11 2019 No.11121055 >>11101366The inertia of the water just allows the coke+mentos reaction to build up more pressure before it starts shooting out its contents. The higher pressure equals more potential energy stored inside and a higher exhaust velocity of the coke, making it go higher.
 >> Anonymous Tue Nov 5 21:03:34 2019 No.11121074   >>11120997pretty sure it means there are two check valves in series there
 >> Anonymous Tue Nov 5 21:20:01 2019 No.11121120 File: 98 KB, 571x315, engcuck.png [View same] [iqdb] [saucenao] [google] [report] so anyone have any suggestions on how to start this problem?
 >> Anonymous Tue Nov 5 21:25:29 2019 No.11121131 If you're low IQ, is it still possible due to crossing over, independent assortment and random fertilization to conceive a high IQ child?
 >> Anonymous Tue Nov 5 21:28:16 2019 No.11121141 File: 90 KB, 516x380, WhatsApp Image 2019-11-01 at 11.39.36 AM.jpg [View same] [iqdb] [saucenao] [google] [report] >>11121074Yeah the symbol looks similar, but I don't see them irl.
 >> Anonymous Tue Nov 5 21:39:09 2019 No.11121158 >>11121001i want to cuddle with patchy
 >> Anonymous Tue Nov 5 21:46:19 2019 No.11121182 will the 200,000,000 Trees planted by Mr. Beast do anything ?
 >> Anonymous Tue Nov 5 21:48:34 2019 No.11121193 >>11121131gauss' mother was illiterate and his father wasn't much better apparently
 >> Anonymous Tue Nov 5 22:01:36 2019 No.11121214   >>11121182Yes, it will do "something"
 >> Anonymous Tue Nov 5 22:25:05 2019 No.11121253 For stochastic processes, or random processes, does it make sense to vary more than one parameter at a time, i.e. amplitude and phase for a sinusoidal signal?or would it make more sense to just vary amplitude?
 >> Anonymous Wed Nov 6 00:27:00 2019 No.11121519 How do you know when to convert from degrees to radians?
 >> Anonymous Wed Nov 6 00:28:17 2019 No.11121520   >>11121519most formulas require angle to be in units of radians
 >> Anonymous Wed Nov 6 00:28:49 2019 No.11121522   >>11121519if an answer states it wants the answer in one or the other. also typically on diagrams it's better to use degrees
 >> Anonymous Wed Nov 6 00:31:27 2019 No.11121527 >>11121519You almost exclusively just use radians for calculations, although how you present your results depends on the particular requirements and ultimately your choice. Specifically, if for example I'm just trying to describe a system or an image geometrically I'd probably use degrees.
 >> Anonymous Wed Nov 6 01:33:06 2019 No.11121607 How do I prove that a function has a global minimum or maximum in all of its domain without using derivatives? I'm talking specifically about e^(-x^2)
 >> Anonymous Wed Nov 6 02:32:46 2019 No.11121682 >>11121182/an/ here, they say they're collaborating with the Arbor Day Foundation to plant native trees species on habitats suitable for restoration across multiple countries. There is some debate about whether the foundation will manage the sites to ensure that secondary succession will properly take place and not just abandon the sites for deer and shit to strip the understory before it can grow properly. Other than that, these areas they say they'll plant on are already ecologically degraded (like mining sites) so its a net positive trying to restore it. >inb4 China and Brazil destroy more natural land so why bother restoring already degraded habitats on other fucking continents.
 >> Anonymous Wed Nov 6 02:44:04 2019 No.11121694   >>11121182it's only 20million, which is 0.000666% of the total trees now, so sure it might do something, but not much.
 >> Anonymous Wed Nov 6 03:56:18 2019 No.11121790 Is the echo a manifestation of sound waves being reflected?
 >> Anonymous Wed Nov 6 04:21:21 2019 No.11121819 File: 25 KB, 770x332, helppls.png [View same] [iqdb] [saucenao] [google] [report] How does someone find the appropriate characteristic equation for the expression above?What can I search for to refresh on that sort of thing?
 >> Anonymous Wed Nov 6 08:00:21 2019 No.11122011 >>11121607e^x is strictly monotonic increasing, so a global minimum/maximum of f(x) is also a global minimum/maximum of e^f(x). -x^2 has a global maximum at x=0 (it's zero at x=0 and negative everywhere else).
 >> Anonymous Wed Nov 6 10:24:35 2019 No.11122262   >>11121790Basically yes
 >> Anonymous Wed Nov 6 13:44:46 2019 No.11122724 Chemistry noob here.I need to clean a platinum crucible that has some manganese tungsten oxide (MnWO4) on it.What chemical should I use to dissolve it?If you have an idea what acid I should use please also tell me the concentration/temperature needed.
 >> Anonymous Wed Nov 6 13:52:52 2019 No.11122746 File: 1 KB, 123x110, 2.jpg [View same] [iqdb] [saucenao] [google] [report] what's this symbol called?
 >> Anonymous Wed Nov 6 14:04:25 2019 No.11122775 How would I go about for sketching sinc(200pit)sinc(2100pit)?Fourier transform gives me (1/200)*rect(f/200)*(1/2100)*rect(f/2100)Don't really know where to go from here or how to even carry out this multiplication
 >> Anonymous Wed Nov 6 14:33:57 2019 No.11122853 >>11121607Lemma 1: Let g be a strictly increasing function. Then x is an extremum for f if and only if x is an extremum (of the same type) for g composed with f.Proof: exerciseLemma 2: The function -x^2 has a single local maximum, occuring at x = 0. It is also its global maximum.Proof: High school math.Now apply lemma 1 and lemma 2 for f(x) = -x^2 and g(y) = e^y
 >> Anonymous Wed Nov 6 14:44:30 2019 No.11122868 Boyle's law says PV = constantBut what if I add a few molecules in a container? The pressure will increase but the volume will stay the same. How does it work?
 >> Anonymous Wed Nov 6 15:02:31 2019 No.11122917 >>11121607That's incomplete, Boyle's law says that PV remains unchanged in a closed system.If you add molecules then the system isn't closed anymore, so there's no reason Boyle's law should still hold.
 >> Anonymous Wed Nov 6 15:03:34 2019 No.11122919 >>11122917Also meant for >>11122868, I don't know why the fuck I linked that other post.
 >> Anonymous Wed Nov 6 15:22:49 2019 No.11122957 >>11122917Ah thanks
 >> Anonymous Wed Nov 6 16:29:18 2019 No.11123156 >>11122868You want the ideal gas law: PV/nT=R, where P=pressure, V=volume, n=quantity (number of molecules), T=temperature, R=ideal gas constant (= product of Boltzmann constant and Avogadro constant).If you increase n while keeping V and T constant, P increases in proportion.Boyle's law: P∝1/V => PV∝1Charles's law: V∝T => V/T∝1Avogadro's law: V∝n => V/n∝1Gay-Lussac's law: P∝T => P/T∝1The ideal gas law combines the above into PV∝nT => PV/nT∝1
 >> Anonymous Wed Nov 6 16:47:03 2019 No.11123216 >>11122868>PV=constantFor a given number of molecules/mass of gas.
 >> Anonymous Wed Nov 6 16:52:03 2019 No.11123222 >>11122746Denotes a binary relation. Seems to be used mostly in set theory and is read as "corresponds to"
 >> Anonymous Wed Nov 6 18:13:59 2019 No.11123397 File: 93 KB, 867x405, file.png [View same] [iqdb] [saucenao] [google] [report] can someone explain this?
 >> Anonymous Wed Nov 6 18:35:29 2019 No.11123448 >>11120908Two dice are rolled. The roller says at least one dice rolled a 6. What is the probability that the sum of both rolls is 7?My answer is 1/6 here because you need a 1 to get a sum of 7.Now what if at least one dice rolled a 5. What is the probability the sum is 7?Again my answer is 1/6 because you need a 2 to get a sum of 7.Am I doing something wrong here? The answers seem too obvious and I am questioning myself.
 >> Anonymous Wed Nov 6 19:04:29 2019 No.11123549 >>11122724Interesting. I don't know.Hübnerite is apparently a good source of tungsten, so look up how it's refined.Conc. hydrochloric acid sounds like your best bet, since MnCl2 seems the most soluble, and similar to the refining of CaWO4 to make tungstic acid.https://en.wikipedia.org/wiki/Solubility_tablehttps://en.wikipedia.org/wiki/Tungsten_trioxideAlso try concentrated lye, which is used in wolframite (mix of Fe and Mn tungstates) processing
 >> Anonymous Wed Nov 6 19:22:09 2019 No.11123607 >>11121519If the person you're talking to has completed high school math
 >> Anonymous Wed Nov 6 19:23:38 2019 No.11123612 >>11121519see angles in terms of pi, you’re using radians, see angle that’s quite large with numerical representation that’s quite small, its radians, doing physics problem? probably degrees
 >> Anonymous Wed Nov 6 20:19:24 2019 No.11123783 File: 489 KB, 961x1000, curled.png [View same] [iqdb] [saucenao] [google] [report] >>11121253Illegible question, try rewriting in a clear fashion.>>11121819$\frac{ \partial ^2 u}{\partial x^2} - 2 \frac{\partial ^2 u}{ \partial x \partial y} + \frac{ \partial ^2 u}{\partial y^2}= (\frac{ \partial ^2 }{\partial x^2} - 2 \frac{\partial}{ \partial x \partial y} + \frac{ \partial}{\partial y^2}) u=0$.Now you've got a nice operator that indicates the direction in which u doesn't change, and you'll multiply it by $\partial y^2$ and cancel stuff out, because we can't have fractions with empty numerators.As always for problems in calc and DEs, in doubt, turn your brain off and think "what would a physicist do?">>11123448There are 36 possible results for throwing two dice. There are 11 cases where one is 6 (6 where the first one is 6, 6 where the second one is, and we remove the double). Out of those eleven, there are two where the sum is 7. That gives 2/11.Same technique works for five.
 >> Anonymous Thu Nov 7 00:42:36 2019 No.11124377 how do i set up a triple integral to find the volume of a paraboloid between two planes using spherical coordinates? really just, how do i convert a paraboloid to spherical coordinates?
 >> Anonymous Thu Nov 7 01:50:56 2019 No.11124498 I am looking into the theory of linear regression with random variables instead of having samples.When we have m samples with n features then linear regression becomesB=(X^TX)^-1(X^TY)Where X is a m by n+1(it has a 1 insert for the constant coefficient) matrix.But what about the case where we don't a sample data set but instead we have information about the regressors? Like their variance and variance, there is a theory on how to do this but I cant find it and google only returns the first model.Can someone point me to a specific name or book?
 >> Anonymous Thu Nov 7 02:40:42 2019 No.11124557 >>11124377> how do i convert a paraboloid to spherical coordinates?Put the focus at the origin; then it's justr = r*cos(φ)+d => r = d/(1-cos(φ))where d is the distance of the focus from the directrix.
 >> Anonymous Thu Nov 7 05:40:42 2019 No.11124822 >>11120908Let's say I have some odd shaped region given by two functions. I'm curious if there is some "standardized" way to coordinate transform this region into a circle and compute the area from there. I can definitely just compute the area of the region and then solve for the radius of the circle but I'm curious about trying to get this whole "coordinate transformation" to click with me.
 >> Anonymous Thu Nov 7 08:58:48 2019 No.11125045 >>11123549Thanks, yesterday I tried it with hot diluted HNO3 and it didn't seem to do anything, so today I decided to put it in an oven with some Na2WO4 and heat it to 1100°C for a few hours, since that was used as a solvent for the hübnerite for high temperature solution crystal growth in the first place.Hope it doesn't fuck up my crucible.If it doesn't clean it I'll just reuse the crucible as is.
 >> Anonymous Thu Nov 7 10:05:40 2019 No.11125188 >>11122746Entspricht
 >> Anonymous Thu Nov 7 12:07:35 2019 No.11125432 >>11125188basiert
 >> Anonymous Thu Nov 7 12:23:20 2019 No.11125462 >>11124822In general, an arbitrary shape cannot be linearly transformed into a circle
 >> Anonymous Thu Nov 7 12:27:34 2019 No.11125467 File: 21 KB, 575x241, SumatraPDF_2019-11-07_20-26-21.png [View same] [iqdb] [saucenao] [google] [report] i don't get it. what says that i'm allowed to pull the minus sign outside the parentheses like that in the last equation?
 >> Anonymous Thu Nov 7 12:30:25 2019 No.11125471 >>11125467(-A) = (-1×A) = -1(A) = -(A)proof: trivialI hate pure math so much
 >> Anonymous Thu Nov 7 12:31:48 2019 No.11125474 >>11125462I don't think he's talking about linear transformation
 >> Anonymous Thu Nov 7 12:33:08 2019 No.11125478 >>11125467It reads(-a)b = -(ab)right there
 >> Anonymous Thu Nov 7 12:41:09 2019 No.11125487 >>11125471>>11125478it would be easy if it said -((-1)(-1)) but -(ab)=(-1)(-1) is just confusing
 >> Anonymous Thu Nov 7 12:58:28 2019 No.11125514 >>11125487Yeah. Any book that spends the first couple chapter sperging out of elementary definitions like what "A
 >> Anonymous Thu Nov 7 13:28:53 2019 No.11125598
 >> Anonymous Thu Nov 7 14:06:37 2019 No.11125683 >>11124498Bumpin
 >> Anonymous Thu Nov 7 14:18:38 2019 No.11125705 >>11122775bump
 >> Anonymous Thu Nov 7 16:08:17 2019 No.11125960 File: 1 KB, 139x79, firefox_2019-11-07_23-04-40.png [View same] [iqdb] [saucenao] [google] [report] How can I show that the limit does not exist?
 >> Anonymous Thu Nov 7 16:39:03 2019 No.11126032 How do you cope with being one of the lower IQ individuals in the family? I find it hard to believe that I can actually get gud at math when I'm still in statistics and my younger sister is in calculus! Blackpill if there ever was one.
 >> Anonymous Thu Nov 7 16:41:00 2019 No.11126038 >>11125960Sign of denominator for x<0 and x>0.
 >> Anonymous Thu Nov 7 16:42:19 2019 No.11126042 >>11126038Thought it said x instead of |x|. Never mind.
 >> Anonymous Thu Nov 7 16:43:49 2019 No.11126048 >>11126038I'm a total retard. Just show that the numerator doesn't go to zero but the denominator does. Basic HS math.
 >> Anonymous Thu Nov 7 16:51:49 2019 No.11126065 How long does it take for the body to deal with sugar?Let us start with a soda's worth.
 >> Anonymous Thu Nov 7 17:13:04 2019 No.11126130 what's the downside to very high voltage batteries? EVs these days have 400V batteries but for charging to be even faster, the voltages need to be in the ranges of 800+ for charge times (almost) comparable to ICE refuelingwhat's stopping manufacturers from doing this? Is it unsafe? hard to make? Please explain like you would to a child, thanks.
 >> Anonymous Thu Nov 7 20:14:55 2019 No.11126546
 >> Anonymous Thu Nov 7 21:01:53 2019 No.11126630 >>11126130To increase energy capacity, you can connect cells in parallel (low voltage, high current) or in series (high voltage, low current).The parallel case typically requires load balancing: ensuring that the current is divided equally amongst cells, which requires some amount of circuitry per cell. And if you have hundreds of them, that's going to cost. An added factor is that you need thick cables to carry thousands of amps.With the serial case, the same current flows through each cell in the chain; there's no need to actively balance them. And you don't need thick cables.In practice, you use a combination of the two: multiple cells wired in series to produce a high-voltage battery, then a few such batteries wired in parallel, with a regulator circuit for each battery. The number of batteries versus the number of cells per battery will be a trade-off of several factors.The limiting factor on voltage is partially safety, and partially the cost and efficiency of the electronics. Components which can handle significantly more than a few hundred volts are somewhat niche items, so compared to more mainstream components they don't have the same economies of scale (making them more expensive), nor have they had the same amount of R&D (making them less efficient).
 >> Anonymous Fri Nov 8 00:24:05 2019 No.11127002 File: 29 KB, 452x678, he loves it.jpg [View same] [iqdb] [saucenao] [google] [report] Hey anyone here do cognitive neuroscience? I participated in a cognitive task experiment recently using an EEG, and the experimenter said that i have an unusual amount of activity at electrode T7 and TP9 ((?) it could be TP7 and T9, i cant remember exactly) even when not doing the tasks, which they hadn't seen in the other participants. I assume there is an international standard for EEG caps, but i haven't been able to find what brain regions + functions relate to what electrode placements. So if there is anyone here who does work with EEGs or knows about them, can you let me know what these electrodes were recording? Broadly speaking it seems like the left temporal lobe, but i don't know anything more than that.
 >> Anonymous Fri Nov 8 01:06:10 2019 No.11127077 We dont need to exceed escape velocity to get outof earth if we have constant acceleration. Then can we escape event horizon that way?
 >> Anonymous Fri Nov 8 01:54:32 2019 No.11127139 What determines how much metabolic energy the brain can access over the course of a single day?
 >> Anonymous Fri Nov 8 04:38:23 2019 No.11127399 Can daylight saving time screw up your circadian rhythm? I usually fall asleep at the same time every day around 10:30 or so and wake up at between 5:00 to 5:30. For the last few days I've been waking up between 4 and 4:30 and been finding it hard to fall asleep quickly for that last hour. I've never been as disciplined about my sleep schedule as I have this year so I wouldn't have noticed if it's affected me before.
 >> Anonymous Fri Nov 8 05:36:49 2019 No.11127484 >>11120908Guys I wanna make small vacuum chamber to remove air bubbles form epoxy mixture.Now i dont know these things well so bare with me.I have a small glass cylinder with silicon lid that seals pretty well,I calculated the volume of the cylinder to be 24 cm^3.I wanna attach a syringe on the lid in hope to remove air and hopefully air bubbles.Will it work?What size of syringe do I need? (in ml)
 >> Anonymous Fri Nov 8 08:41:51 2019 No.11127712 >>11120908It has been on my mind that a system cannot measure itself. It cannot account for its own thinking. Where can I read more about this? What are the theoretical limits on the ignorance of such a measuring system? This interests me because it means that the measurer is a singularity in its own (scientific) account of the world he lives in. Second, is this concept ever applied to the fields of psychology and sociology? It's well known that people may adjust their behaviour when they are told they should act so-and-so: this is an inherent weakness of the said fields, and I hope this issue has been properly disserted by logicians, philosophers and/or scientists.
 >> Anonymous Fri Nov 8 09:00:22 2019 No.11127733 >>11127077No. It's not just that the escape velocity is "greater than light speed" (even though this doesn't make sense in relativity), it's that the interior of a black hole is utterly inescapable period. There are no physical trajectories, whether freefall or accelerating, that can escape out of a black hole from inside.
 >> Anonymous Fri Nov 8 10:39:02 2019 No.11127925 I want to double the value 3 six times and sequentially add them together, like 3+6+12+24+48+96. How can I represent this using sigma?
 >> Anonymous Fri Nov 8 10:54:27 2019 No.11127953   >>111279253+(2)3+(4)3+(8)3+(16)3...[eqn]\sum_{n=0}^52^n\cdot3[/eqn]
 >> Anonymous Fri Nov 8 11:17:52 2019 No.11127993 scientifically speaking, why do people who smoke before lectures see the need to sit right fucking next to someone to choke them with their putrid cigarette scent when there are many available seats away from people
 >> Anonymous Fri Nov 8 11:35:51 2019 No.11128030   File: 233 KB, 665x665, 20190905_072940.jpg [View same] [iqdb] [saucenao] [google] [report] >>11127993Why do people like eat noisily, slurping noodles in the library?Why do people ask a million inane questions per lecture? Why do people whip out their laptop in front of you and start browsing bullshit when they should be paying attention?At least I wash my hands.
 >> Anonymous Fri Nov 8 11:37:21 2019 No.11128034 >>11128030God I want to be the bunny
 >> Anonymous Fri Nov 8 11:42:18 2019 No.11128046   >>11128034So in our computer lab there is an emergency telephone that's very obviously for...emergencies only. Last week I was in there doing some work and hear some commotion from an african american student."Hello? Yes??" [pause] "There's no paper in the printer." [longer pause] "I said there's no paper in the printer! We need more paper!" Everyone is looking. "Oh...okay." he hung up and left the lab entirely.
 >> Anonymous Fri Nov 8 11:46:39 2019 No.11128056 File: 1.31 MB, 640x360, 124868773.gif [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Fri Nov 8 11:49:16 2019 No.11128067 https://math.stackexchange.com/a/433301is there an error in this answer? the person wrote 2(a+1) then in the next line wrote 2a+1shouldn't it be 2a+2?
 >> Anonymous Fri Nov 8 11:50:16 2019 No.11128069   >>11128056*smokes an extra cig just before class, just for you*
 >> Anonymous Fri Nov 8 12:42:11 2019 No.11128162 Ignoring atmospheric effects, if I hold up a plate in such a way that its surface normal points towards the sun, will the solar irradiance on the plate be independent of latitude and time of day?
 >> Anonymous Fri Nov 8 12:43:13 2019 No.11128163   >>11128162Ignoring the atmosphere, yes, it approximately makes no difference.
 >> Anonymous Fri Nov 8 12:51:51 2019 No.11128183 >>11128067I don't know which exact line you are referring to, but if it is the one I think it is then the value x/2 has to be strictly smaller than 2(a+1), so it can't be 2a+2 and thus they take 2a+1 (and 2a since x/2 should also be equal or greater than 2a)
 >> Anonymous Fri Nov 8 12:57:15 2019 No.11128202 >You need to replace the heating system in your house. The heating contractor is offering you a system that supplies energy at the maximum rate of 40 kW. You know that your house loses energy at the rate of 1.3 kW per degree difference in temperature between inside and outside of the house. The minimum winter temperature in you rarea is−15oC. You want to maintain 20o indoors. Should you go with the heating system recommended by your contractor?Is this a trick question? 1.3 kW per degree difference in temp means, at worst, we lose 45.5 kW, which is too much for the system being offered to handle (since we want to maintain 20oC inside), right?
 >> Anonymous Fri Nov 8 12:58:58 2019 No.11128208 >>11128163Thanks anon.
 >> Anonymous Fri Nov 8 13:58:41 2019 No.11128332   >>11128202No, you are correct. You do not want the option he is offering.
 >> Anonymous Fri Nov 8 14:16:40 2019 No.11128371 Hi, /sci/. I'm looking for the most non-brainlet computer science education/regimen I can possibly find. Normally, I'm a /g/ poster, but the average /g/ user shies away from math and all that stuff. Thanks.
 >> Anonymous Fri Nov 8 14:42:00 2019 No.11128442 If you cheat on a test, fail, and the professor posts the grade online, is it safe to assume you didn't get caught?If you were to get caught, would the professor not have bothered posting the grade?
 >> Anonymous Fri Nov 8 14:42:54 2019 No.11128444 >>11128442Stop cheating
 >> Anonymous Fri Nov 8 14:48:35 2019 No.11128458 >>11128332Thanks mate, also regarding questions about gases in thermodynamics, is it fair to assume that they are ideal? For example, I'm given a question about argon and I'm supposed to find something about volume/pressure/etc, is it fair of me to just assume it's an ideal gas so I can use the ideal gas law?
 >> Anonymous Fri Nov 8 14:56:05 2019 No.11128488 File: 97 KB, 413x413, 20190413_062333.jpg [View same] [iqdb] [saucenao] [google] [report] >>11128458It depends. Ideal gas law is best at pressures that are small compared to critical pressure and temperatures that are high compared to critical temperature. Otherwise, use a compresibility factor/chart. (Pv=ZRT) You can also use some other equation of state like Van der Waals. There are many options to chose from!
 >> Anonymous Fri Nov 8 14:58:05 2019 No.11128496 >>11128488ok ty again bby
 >> Anonymous Fri Nov 8 16:23:36 2019 No.11128694 If a polyhedron has 24 vertices and each vertex is connected to 3 edges, how do you calculate how many edges it has?
 >> Anonymous Fri Nov 8 16:39:35 2019 No.11128732 File: 30 KB, 493x260, 110819.jpg [View same] [iqdb] [saucenao] [google] [report] hi everyone i don't quite understand this problem, my professor didn't talk about this. i don't know what a+bi form means or how to solve this
 >> Anonymous Fri Nov 8 16:44:56 2019 No.11128751 >>11128732a+bi is complex form, real part is a and bi is imaginary(x-5)^2=-49x-5=+/-7ix=5+/-7i
 >> Anonymous Fri Nov 8 16:47:31 2019 No.11128756 >>11128732if you take the square root of both sides, you end up with x - 5 = sqrt(-49). i = sqrt(-1), hence -49 = 7i.x = 5+7i
 >> Anonymous Fri Nov 8 17:28:19 2019 No.11128856 My professor said that lim (a_n)^(1/n) = lim (a_(n+1))/(a_n)) why is this true? What's the reasoning behind it?
 >> Anonymous Fri Nov 8 17:37:33 2019 No.11128878 >>11127925Like sigma (from k=1 to 6) 3*2^k?
 >> Anonymous Fri Nov 8 20:06:26 2019 No.11129201 File: 112 KB, 768x1024, 1573190182703m.jpg [View same] [iqdb] [saucenao] [google] [report] >>11120908Particle physics question.Suppose an oxygen atom is moving at a constant velocity through space. It passes by another oxygen atom, and immediately binds with it. Does it slow down correspondingly? I'm guessing the answer is yes, but I wanted to ask anyway.
 >> Anonymous Fri Nov 8 20:15:50 2019 No.11129211 >>11128856What is a_n? And the limit as what tends to what?You need to clarify the question.
 >> Anonymous Fri Nov 8 21:45:24 2019 No.11129435 >>11120908why do they mean by, that, during solving, during solving by FEM/FVM people say that solution in particullar "time-step" must "converge"tl;dr why in FEM solutions must "converge" to some arbitrary values
 >> Anonymous Fri Nov 8 21:47:42 2019 No.11129441 >>11129211_ denotes subscript and the limit is almost certainly infinity, use common sense
 >> Anonymous Fri Nov 8 23:10:29 2019 No.11129616 if you have 2 blankets and one is warmer than the other, which one should you place on top? or it doesn't matter?
 >> Anonymous Fri Nov 8 23:36:29 2019 No.11129667 >>11129435For FVM (I don't know FEM), certain simplification are made to the governing equations, this means that the equations being solved aren't actually the correct equations, so the answer we get is an approximate one. This is compensated for by solving the equations multiple times and using the solution of each iteration for the next. If this is done correctly, the solution will converge to the correct value.
 >> Anonymous Fri Nov 8 23:59:15 2019 No.11129721 >>11129441The information that's missing is that $(a_{n})_{n \in \mathbb{N} }$ is a sequence of positive numbers, otherwise the n-th root may be undefined when n is even. The full statement is the following:Let $(a_{n})_{n \in \mathbb{N} }$ be a sequence of positive real numbers. Then:$\liminf_{n \rightarrow \infty} \frac{a_{n+1}}{a_n} \leq \liminf_{n \rightarrow \infty} \sqrt[n]{a_n} \leq \limsup_{n \rightarrow \infty} \sqrt[n]{a_n} \leq \limsup_{n \rightarrow \infty} \frac{a_{n+1}}{a_n}$. Of course when a sequence is convergent then $\liminf = \limsup$ and thus you get the equality you were told. I'll explain assuming the limits are both convergent to a real number kThe intuitive reason is simply because $\lim \frac{a_{n+1}}{a_n} = k < \infty$ basically just tells that the further you go into the sequence, the closer each element becomes to just the previous element times k, or in other words $a_{n+1} \approx ka_n$. Apply that for every element to the previous one, and you find that (very roughly), $a_{n} \approx k^{n-1}a_1$. Of course, this estimate could be very inaccurate for small n, but limits don't care about small n. So even if the first term of the sequence may be annoying at first, the bigger n becomes the more irrelevant that first element becomes, since the whole product just behaves like the natural powers of k. And you may already notice what happens if you take the n-th root, in that case. For the formal proof, you might want to take advantage of $\frac{a_n}{a_{n-1}} \frac{a_{n-1}}{a_{n-2}} ... \frac{a_{m+1}}{a_m} = \frac{a_{n}}{a_m}$, for n>m, and also the definition of a limit. It's just working with some inequalities but it should be manageable.
 >> Anonymous Fri Nov 8 23:59:18 2019 No.11129722 >>11129616The equivalent thermal resistance is the same either way so it probably doesn't matter. I'm not entirely sure though.
 >> Anonymous Sat Nov 9 03:39:22 2019 No.11130101 I set A' is a complement to set A, does an element from set A' complement an element from set A.
 >> Anonymous Sat Nov 9 03:50:08 2019 No.11130112
 >> Anonymous Sat Nov 9 03:59:58 2019 No.11130123 >>11130112What does it mean for an element to complement another element? What does it mean for a thing to complement another thing?
 >> Anonymous Sat Nov 9 04:25:38 2019 No.11130157 >>11130123it doesn't mean anything. the answer is "no", because the question doesn't make sense.
 >> Anonymous Sat Nov 9 04:31:58 2019 No.11130167 >>11130157Couldn't you have said that to begin with?
 >> Anonymous Sat Nov 9 04:57:19 2019 No.11130200 >>11130167sure
 >> Anonymous Sat Nov 9 09:33:02 2019 No.11130527 "the process of digestion normally takes between 24 and 72 hours"Can stool already in the bowels be influenced by digestion happening elsewhere in the body?I shat green a mere fourteen hours after eating kale. Trying to figure out if my digestion cycle is abnormally fast.
 >> Anonymous Sat Nov 9 10:11:43 2019 No.11130647 >>11129616I think the warmer blanket below is better, since the area with a warmer temperature will be concentrated in a smaller volume that way.
 >> Anonymous Sat Nov 9 12:47:44 2019 No.11131000 I'll be re-enrolling as a math major for winter term after a little over two years away from school. The minor is CS, and my first class load will be vector calc, a second programming class (I took the intro already), and physics w/ calc. How would you structure your study plan knowing this? I'm thinking I'll just grind maths, I'm working through Spivak's Calc right now for a refresher, it's obviously way more rigorous than Stewart's calc which is what the class uses, so I think solely studying that will be good enough prep.On a related note, how many things can you effectively study in parellel?
 >> Anonymous Sat Nov 9 12:51:47 2019 No.11131010 File: 42 KB, 420x279, DarkMatter.gif [View same] [iqdb] [saucenao] [google] [report] This is a dumb question, but I'll try to explain my logicPic related looks like a logarithm. Logarithms are similar to the arccosh(x) function, like so:>$arccosh(x)=ln(x+\sqrt{(x-1)(x+1)})$Is it fair to assume that the distribution of mass follows an arccosh(x) function, and from there, try to fit the data to it?The arccosh(x) function is undefined on (-1, 1). Could this undefined region correspond to the radius of the galaxy's supermassive black hole? Does it correspond to the average mass of the galaxy?
 >> Anonymous Sat Nov 9 14:38:03 2019 No.11131230 Are there any good books about understanding human behavior that aren't psychological mumbo gumbo?
 >> Anonymous Sat Nov 9 14:53:28 2019 No.11131254 >>11128878I got an answer from another anon, but that post is removed. It said n=0 to 5. But yes, you're right with 3 * 2^n.
 >> Anonymous Sat Nov 9 18:08:40 2019 No.11131677 >>11131669>regionOh, right.There's the Riemann mapping theorem. I think there was a constructive proof in Bishop's constructive analysis, but it's probably by iteration.By the by, the radius thing doesn't work for that.
 >> Anonymous Sat Nov 9 21:02:51 2019 No.11132095 So when lights are on, photons bounce around and that's how I see colors and stuff. When I turn off the lights, the bulb no longer emits photons, but how do objects absorb all photons so fast? Is it always guaranteed that there will be objects that absorb all visible EM wavelengths?
 >> Anonymous Sun Nov 10 01:21:27 2019 No.11132624 >>11132095Light travels at 300 m/μs, so unless you're in a huge room it's going to bounce off multiple surfaces every microsecond. And if that isn't enough to absorb it all, it will travel through 300 km of air per millisecond, which will absorb a lot (notice how much dimmer the sun is when it's near the horizon compared to overhead).IOW, the only way it's going to keep bouncing around for an extended period without being absorbed is if it's inside a large container with perfectly reflective surfaces and no atmosphere (vacuum).
 >> Anonymous Sun Nov 10 06:14:56 2019 No.11132976 File: 8 KB, 814x262, IMG_20191110_121327.png [View same] [iqdb] [saucenao] [google] [report] For a motor pump, what would "the electric power consumed" mean? The power before it enters the pump? The power after it goes through the motor pump?It's for a fluid mechanics problem. Pic related.
 >> Anonymous Sun Nov 10 06:55:58 2019 No.11133059 You know when you're learning physics you start off with all this specific stuff that only applies in particular situations and then you move on to some more general techniques that still seem kind of unrelated and then finally you do classical mechanics properly and it brings it all together? Is there a something analogous to that final step that makes it all work for statistics?I know a lot of statistics and there are vague strands relating it all together but on the whole it's kind of a big mess.
 >> Anonymous Sun Nov 10 09:36:43 2019 No.11133317 Why does wind form?
 >> Anonymous Sun Nov 10 09:51:22 2019 No.11133345 >>11133317Not a meteorologist but on a small scale differential heating of the air (ie as the land heats up during the day vs the relatively stable temperatures over water) will give you a difference in pressure and air will flow from high to low. Where I live in summer we get a reliable cool wind off the ocean on a hot afternoon because of this. Large scale patterns are probably the same effect + the earth's rotation (+ tidal forces maybe?) + some degree of self-organising.
 >> Anonymous Sun Nov 10 11:20:23 2019 No.11133571 File: 245 KB, 960x1540, 1569967590800.jpg [View same] [iqdb] [saucenao] [google] [report] What would be the most efficient way to go about starting to study biology?It caught my interest and I was wondering where I should start, I understand studying biology implies prerequisites in chemistry, physics and math so I was wondering what order/what resources I should look into.
 >> Anonymous Sun Nov 10 11:40:26 2019 No.11133622 >googling for 30 minutes looking for an answer>don't understand shit about what people are saying>open another quora link>perfect short answer that explains everything I wanted to know>it's written by a fucking "Middle School Student who does more math than he should"
 >> Anonymous Sun Nov 10 12:04:08 2019 No.11133684 File: 3.09 MB, 4000x3000, IMG_20191110_180020.jpg [View same] [iqdb] [saucenao] [google] [report] What now besides taking log n before sums
 >> Anonymous Sun Nov 10 12:08:40 2019 No.11133693 >>11133684Just reuse the trick that went into the first one, that is, multiply by n^2 to remove both sums.
 >> Anonymous Sun Nov 10 12:20:55 2019 No.11133724 >>11133693but the second sum starts at i, not 1
 >> Anonymous Sun Nov 10 12:29:29 2019 No.11133756 >>11131669>just study hardI'm trying but I'm looking to increase efficiency based off my very specific goal. Intuitively, I feel that blasting through Spivak's Calculus is my best bet, since it will turn my brain into a muscular monstrosity, but I also see why this is dumb because it is unrelated to any of the courses I'm taking. So I think I'm going to just go hard on Spivak for the brain gains, and balance that out with some review type sessions for the other material for the domain specific knowledge every now and then.
 >> Anonymous Sun Nov 10 12:54:59 2019 No.11133843 >>11133724Oh, didn't see that one.$\Sigma_{i=1}^n \Sigma_{j=i} \log n= \Sigma_{i=1}^n (n-i) \log n = \log n \Sigma_{i=1}^n (n-i)$Evaluating the last sum is left as an exercise to the reader.Tip: split it into the sum of two sums, i.e. $\Sigma (a+b) = \Sigma a + \Sigma b$>>11133756>it will turn my brain into a muscular monstrosity>I'm going to just go hard on Spivak for the brain gainsIt really doesn't work like that. You either seriously overestimate Spivak or you're genuinely stupid enough for the brain gains to actually happen.
 >> Anonymous Sun Nov 10 12:55:55 2019 No.11133845 when is the best time to exercise for the benefit of learning? immediately before studying? immediately after? or just any time during the day?
 >> Anonymous Sun Nov 10 12:58:06 2019 No.11133852 >>11133843do you know what hyperbole is? compared to Stewart's Calculus, it will certainly get my brain better at problem solving and the abstract reasoning that math demands. I've already read half of it, and it definately made me much better at maths, and focusing / thinking abstractly in general. I mean I can't say it's the sole source, but I feel like it was the single largest contributor with Valenza's abstract algebra book a close second.
 >> Anonymous Sun Nov 10 13:07:08 2019 No.11133879 >>11133843ah shit thanks, havent done math in a long time
 >> Anonymous Sun Nov 10 13:11:54 2019 No.11133892 >>11133724Twice the sum is:1+...+n+n+...+1= n(n+1)So the sum is n(n+1)/2.More generally, for any arithmetic sequence (a sequence where the gap between adjacent elements is constant) the sum is the total number of elements times their average: n*(lo+hi)/2. The average of the first and last elements is equal to the average of the second and last-but-one elements and the third and last-but-two and so on. Thus you can replace every element with the average without changing the sum.
 >> Anonymous Sun Nov 10 13:17:26 2019 No.11133913 >>11133571>most efficientjust start right now and review/learn prereqs only as needed, as they come up. strictly on an as needed basis.
 >> Anonymous Sun Nov 10 14:20:21 2019 No.11134088 is it better to go to a shitty local, state uni where i get free rent and a freelance, fun, low weekly hour job from home or is it better to go to a somewhat decent state uni, pay rent, and probably not have the cushy job anymore?
 >> Anonymous Sun Nov 10 14:25:41 2019 No.11134115 >>11134088freelance was the wrong word, it's more like work whenever i want, but a certain amount of routine work must be done every week (which takes about 20 hours to do). it's the ideal job as a student due to this and it being doable from home, imo. so I know my studies will suffer if i move and have to work to pay rent in conjunction with studying. but the school is way better; the local uni is like a community college, the other one is probably the best school in the state for my major.
 >> Anonymous Sun Nov 10 15:15:28 2019 No.11134271 >>11133756Take color coded notes in class, make them pretty so you can admire them, dream of them, and feel proud.Before the exam, skim over all your notes, condense them into a 1-page "cheat sheet," then remember as much of it as you can. Don't bother with practice problems, that's what homework's for.Takes like, a couple hours a month, tops, and you will destroy the exams.
 >> Anonymous Sun Nov 10 16:03:52 2019 No.11134474 >>11134271other anon, just try anki im not super smart and spend hours weekly on vidya, despite all of that im on 3rd semester at uot that's around top 800 in europe (i know its not prestigous but still) with all subjects passed so far, meanwhile half of my year already dropped out, even passed physics on first try despite it starting at intermediate level and me not ever learning it beforejust run it everyday, add new shit that you've had that day on uni, repeat what you have to and you're golden
 >> Anonymous Sun Nov 10 16:37:02 2019 No.11134610 Is there any game that you can play to increase your logic / critical thinking?I'm solving IMO problems in my free time but I think I might as well try to play some games because they are more fun. I heard things like FTL or StarCraft helps. Is that true?
 >> Anonymous Sun Nov 10 17:04:56 2019 No.11134699 a|bdoes this mean, a such as b?
 >> Anonymous Sun Nov 10 17:21:34 2019 No.11134731 >>11134699divides?
 >> Anonymous Sun Nov 10 17:24:51 2019 No.11134738 >>11134610Keep solving IMO problems. If you want to increase your logic / critical thinking for competitions, nothing will help you prepare better than solving actual problems.By playing games you will only become better at playing those games. Improvements in other areas will be pretty much negligible.
 >> Anonymous Sun Nov 10 17:26:00 2019 No.11134743 The question is describe the numbers not(in italics) in interval [-3,3]The answer according to the textbook is both |x| ≤ 3 and -3 ≤ x ≤ 3. Isn't this wrong? Wouldn't this describe the number in the interval [-3,3] instead?
 >> Anonymous Sun Nov 10 17:26:58 2019 No.11134746 >>11134743You are right. The textbook is wrong.
 >> Anonymous Sun Nov 10 17:33:11 2019 No.11134750 >>11134746Great. Hopefully the author just didn't give a shit about proof-reading the basic review and the actual meat of the text will be reliable. I like how this text is written and the breath of the problems even in the opening chapter otherwise.
 >> Anonymous Sun Nov 10 18:13:31 2019 No.11134851 >>11134731a|b and a|c a|(x · b + y · c)
 >> Anonymous Sun Nov 10 18:17:16 2019 No.11134861 >>11120908Someone pls help with this problem:Given: [eqn]C(p) = \int \limits_{0}^{p} \cos{\big( \frac{\pi t^2}{2} \big)} dt[/eqn] and [eqn]S(p) = \int \limits_{0}^{p} \sin{\big( \frac{\pi t^2}{2} \big)} dt[/eqn] prove using maclauring series and integration that: [eqn]C(p) + jS(p) = \displaystyle \sum_{n=0}^{\infty} \frac{(j\pi/2)^np^{2n+1}}{n!(2n + 1)}[/eqn]
 >> Anonymous Sun Nov 10 18:17:18 2019 No.11134862 >>11134851yes. a | b means a is a factor of b, and likewise if a | c, a is a factor of c. so a is also a factor of (x*b + y*c)
 >> Anonymous Sun Nov 10 18:24:23 2019 No.11134872 File: 824 KB, 2722x4096, 1543474435858.jpg [View same] [iqdb] [saucenao] [google] [report] >>11134861This really looks like the kind of problem where you just swap sin and cos for the power expansions, use the ole rule for integration of power series, and evaluate by hand like a retard, did you try doing that?>>11134743Seems like the book is wrong to me.
 >> Anonymous Sun Nov 10 18:24:53 2019 No.11134873 >>11134862thanks
 >> Anonymous Sun Nov 10 18:30:52 2019 No.11134884   >>11134872>This really looks like the kind of problem where you just swap sin and cos for the power expansionsif you apply euler's formula i think c(p) + jS(p) is just the integral of e^(j * pi*t^2 / 2))
 >> Anonymous Sun Nov 10 18:47:23 2019 No.11134923 >>11134884Ye, but there's a difference between answering and spoonfeeding. I'm perfectly content giving an absolutely horrendous answer and leaving anon to use his own insight to better it.
 >> Anonymous Sun Nov 10 18:50:05 2019 No.11134927 >>11134872>Just swap sin and cos for power series...Im dealing with a definite integral tho, how does that look like in the resulting series expansion?>>11134884Dont think ill have to deal with an error function
 >> Anonymous Sun Nov 10 18:56:37 2019 No.11134939 >>11134923well i'm not. i need the practice.from the integral e^(i...), you use the series definition of e to get the integral over the series whose terms are (pi/2)^k *t^(2k)/k!. taking the anti-derivative of each term, you get (pi/2)^k t^(2k+1)/(k!*(2k+1)), i think.
 >> Anonymous Sun Nov 10 18:58:29 2019 No.11134943 >>11134939>(pi/2)^k *t^(2k)/k!(j*pi/2)^k *t^(2k)/k!forgot the j
 >> Anonymous Sun Nov 10 19:08:12 2019 No.11134967 File: 338 KB, 2340x3072, New Doc 2019-11-10 20.06.04_1.jpg [View same] [iqdb] [saucenao] [google] [report] >>11134939>>11134943My apologies anons, the problem was rather trivial and I just got scared due to how ugly it looked.Your insight helped me solve it, thank you very much.
 >> Anonymous Sun Nov 10 19:08:48 2019 No.11134968 File: 277 KB, 800x1131, __kitashirakawa_chiyuri_touhou_and_1_more_drawn_by_blackcat_pixiv__90bdf81df6fb8b2ca7eee515b0cf12ce.jpg [View same] [iqdb] [saucenao] [google] [report] >>11134927Evaluate the indefinite integral (remember the integral of polynomials? Infinite series do the exact same thing, but the sum is infinite), and do the ole F(b)-F(a).The F(b) is "probably" in the n=0 component.>>11134939>>11134943Sounds about right.
 >> Anonymous Sun Nov 10 19:11:33 2019 No.11134974 >>11134968>the F(b)The F(a).>>11134967Is that spanish?
 >> Anonymous Sun Nov 10 19:13:04 2019 No.11134978 >>11134968Post above you is the solved problem my dude. Thanks anyways bro.>>11134974>Is that spanish?Yes (unfortunately)
 >> Anonymous Sun Nov 10 19:54:21 2019 No.11135091 File: 9 KB, 309x191, Screenshot_2019-11-11-02-50-00-234_com.google.android.apps.docs.jpg [View same] [iqdb] [saucenao] [google] [report] >>11120908Does anyone know how to use matlab?I'm supposed to make a matrix that looks like this, using the loop 'for' function.If anyone could help, i'd really appreciate it.I'm a chemistry major, i'm not built for computers
 >> Anonymous Sun Nov 10 19:59:59 2019 No.11135101 >>11135091No idea how to use matlab, but can't you just define a matrix with $a_ij=i*j$ for $j \leq i$ and 0 otherwise?
 >> Anonymous Sun Nov 10 20:02:22 2019 No.11135113   >>11135091k = 1for j from 1 to cols for i from j to rowsmat[i,j] = kk += 1not matlab syntax but i think that's what you're looking for.
 >> Anonymous Sun Nov 10 20:05:27 2019 No.11135118   >>11135113cont.disregard this. you can still use the loops to access the elements on and below that diagonal, from top to bottom, left to right, but you'll still have to figure out the value of Aij
 >> Anonymous Sun Nov 10 20:06:29 2019 No.11135120 >>11135101for j from 1 to colsfor i from j to rowsmat[i,j] = j * inot matlab syntax but you can translate it.
 >> Anonymous Sun Nov 10 20:22:22 2019 No.11135154 >>11135091For i=1:size(a)(2) For j = 1:i a(j) = i*j endendOf the top of my head, should work nontheless
 >> Anonymous Sun Nov 10 21:49:09 2019 No.11135296 Suppose that G is a k-regular graph on 2n vertices. Let G1 be the graph G after attaching a vertex x connected to the first n vertices, and let G2 be the graph G after attaching a vertex x connected to the last n vertices. I need to show that the adjacency matrix of G1 and G2 are similar, is there a good starting point for this?
 >> Anonymous Sun Nov 10 22:15:26 2019 No.11135354 >>11124498>>11131669Basically how to make multivariate linear regression with random variables without having observations available, just having their expected values and variances. The algorithm should minimize the SE
 >> Anonymous Sun Nov 10 23:07:27 2019 No.11135475 >>11135101>>11135113>>11135154>>11135120Thank all of you guys!
 >> Anonymous Mon Nov 11 00:43:08 2019 No.11135732 Any anons with integration bee experience here? I was wondering if either of the two integration technique books in the wiki (Irresistible Integrals by Boros or Interesting Integrals by Nahin) are good primer books for a contest like this. And if so, which one? I'm just looking for the most barebones one at the moment since the contest is within a month and I'm just a freshman fag that wants to be able to do at least one of the integrals.
 >> Anonymous Mon Nov 11 00:44:17 2019 No.11135735 >>11131669>HegelAnything specific I should look for? When it comes to epistemology I'm more aligned with the analytic tradition but you have captured ny attention.
 >> Anonymous Mon Nov 11 00:44:28 2019 No.11135738 >>11120908Is a closed energy loop (100% efficiency) possible?
 >> Anonymous Mon Nov 11 00:54:01 2019 No.11135760 >>11135735To be more exact, I think this issue can be approached from a more modern perspective with system- or information-theory. Actual mathematical theories outlining the limits of Turing machines or something like that (it's not my area of expertise but you get the idea). Does that exist?
 >> Anonymous Mon Nov 11 01:31:31 2019 No.11135844 I was going to make a new thread, but I will just ask here. How do I handle a friend who has adopted the EU theory? Whenever the topic of cosmology is brought up, he looks at me like I am a retard who is a sheep that has been brainwashed by the standard scientific consensus on theories of the universe. He has claimed, gravity can not be proved and Einstein's theory of general relativity is wrong, among other things. I usually try to ask him questions to expose his views, however i have no scientific background
 >> Anonymous Mon Nov 11 01:44:30 2019 No.11135878 >>11135844What's your friends education/research field?
 >> Anonymous Mon Nov 11 01:53:54 2019 No.11135898 which polynomials can we write with coefficients 1 or -1 (binary polynomials) that have real roots?
 >> Anonymous Mon Nov 11 01:57:45 2019 No.11135911 >>11134610what’s ftl? sc2 def keeps me quick witted
 >> Anonymous Mon Nov 11 02:10:26 2019 No.11135938 >>11135898We have -x^3-x^2+x+1 has all real roots. notice a pattern?
 >> Anonymous Mon Nov 11 02:28:06 2019 No.11135978 I'm writing the measures section of a lab report right now. When I refer to the independent variables, do I phrase it as "the first independent variable "measured"...."? It's only a binary variable so I'm just a bit confused as to whether it's correct to use the word "measure".
 >> Anonymous Mon Nov 11 02:34:59 2019 No.11135987
 >> Anonymous Mon Nov 11 02:57:04 2019 No.11136018 im looking for chemical reactions between two liquid substances at stp which are highly endothermic and produce a large amount of highly energetic reactants like molecular hydrogenin the presence of a catalyst is ok as long as it doesnt erode the shit out of the catalystthe safer to handle the betterdoes /sci/ know? thanks in advance
 >> Anonymous Mon Nov 11 03:46:35 2019 No.11136098 I am a computer science student and I am taking a course on quantum mechanics this semester. I hardly understand anything while most of the others (who mostly are CS students as well) seem to understand everything well enough. What are some good sources to learn quantum mechanics for someone without much background in physics like myself?
 >> Anonymous Mon Nov 11 04:03:10 2019 No.11136115 >>11130527I know nothing about digestion, but Kale is like 80% water content so I’d assume all those green fluids got absorbed quickly and mixed with the poopoo
 >> Anonymous Mon Nov 11 04:10:22 2019 No.11136130 >>11134271Is this bait?Practice questions are everything
 >> Anonymous Mon Nov 11 07:09:39 2019 No.11136371 >>11136098How good are your maths? Are you familiar with linear algebra and/or complex numbers?
 >> Anonymous Mon Nov 11 07:58:18 2019 No.11136454 >>11136371Yes, I've had linear Algebra in first semester and complex numbers were part of that.
 >> Anonymous Mon Nov 11 09:21:21 2019 No.11136576 >>11136454Have you also covered orthogonality and eigenvalues? If you know all of this (plus integrals), you should be set for an intro course. But the formalism can be challenging to understand, that's not something computer scientists struggle with. I'm a physics master student and I learned QM through Griffiths, which is a really good book, perhaps more pedagogical Anons know what you need exactly. If you have a specific question I can try to explain it here.
 >> Anonymous Mon Nov 11 09:58:37 2019 No.11136646 >>11136576It's not something just* computer scientists struggle with. My bad.
 >> Anonymous Mon Nov 11 10:07:48 2019 No.11136676 When I first covered QM we used some chapters in Serway Moses and Moyer that go through it's development historically, starting with like the photoelectric effect experiments and working up to atomic orbitals. It's not particularly rigorous but if you're having conceptual problems instead of mathematical ones it might give you something to work with.
 >> Anonymous Mon Nov 11 10:16:46 2019 No.11136715 >>11136576>>11136676Thank you, I'll look into those.
 >> Anonymous Mon Nov 11 11:00:25 2019 No.11136817 File: 54 KB, 400x509, 57182241-fat-fox.jpg [View same] [iqdb] [saucenao] [google] [report] >>11120908Anyone know good resources for curve shortening flow?
 >> Anonymous Mon Nov 11 12:58:41 2019 No.11137101 File: 62 KB, 1280x800, Screenshot_2019-11-11_12-56-54.png [View same] [iqdb] [saucenao] [google] [report] CAN SOMEONE QUICKLY EXPLAIN WHY THIS IS 1.4 AND NOT 2.7I HAVE A TEST IN 1 HOUR AND I STILL CANNOT FIGURE OUT WHY
 >> Anonymous Mon Nov 11 13:26:05 2019 No.11137157 >>11137101GUYS PLEASE FUCK FUCK FUCK
 >> Anonymous Mon Nov 11 13:28:16 2019 No.11137166 >>11135878He is high school educated and works in IT sales.
 >> Anonymous Mon Nov 11 13:29:09 2019 No.11137170 >>11135911Faster than light. It's a rogue-like strategy / resource management game. You can pause but it's a bit intensive near the end.
 >> Anonymous Mon Nov 11 13:40:52 2019 No.11137196 File: 33 KB, 400x524, 09.jpg [View same] [iqdb] [saucenao] [google] [report] >>11137101>>11137157dont leave me out to dry like this bros
 >> Anonymous Mon Nov 11 14:06:16 2019 No.11137268 >>11137196it's faradays law, find the magnetic flux, differentiate, multiply time number of turns of coil (300) and evaluate at 2.if you don't know how to find the magnetic flux then you're probably kinda fucked, permeability*n (of solenoid)*I*0.4*area (of solenoid too)
 >> Anonymous Mon Nov 11 14:26:25 2019 No.11137328 >>11137166If you're not a physicist either then the whole affair is pretty pointless and you should just laugh it off. If he one-ups you once in a while that's ok, you aren't supposed to know everything either, while you can look up experimental verification of general relativity at any point in time and challenge him with that. Either he has a crackpot theory to debunk it or he doesn't have a response at all. If you are an actual physicist it may be worthwhile to look into EU a little bit and lampoon how unscientific it is in detail. It depends on how scathing you want to be, I don't like to insult people but humiliation is sometimes the best way if you really want him to stop believing in conspiracies, there's doubtlessly some psychological research on the topic.
 >> Anonymous Mon Nov 11 14:50:45 2019 No.11137410 How do I calculate the volume percentage of an analyte using GAS CHROMATOGRAPHY?I've been given the response factor AND the areas of peaks
 >> Anonymous Mon Nov 11 14:53:58 2019 No.11137417 >>11137268I know how to find it but I was using the wrong area, I shouldve used .15 instead of .4.15 gives 1V which is the correct answer and I just misread the answer pagefuck me
 >> Anonymous Mon Nov 11 15:54:50 2019 No.11137568 >>11136130No it's literally how I got through college>Practice questions are everything!Yeah, the first time you do them. aka homework. You solve one, you've solved a million
 >> Anonymous Mon Nov 11 15:55:19 2019 No.11137570 >>11135354Alright, let me see if I understand.You have an n-dimensional vector $X = (X_1, ~ ..., X_n)$, where all the $X_i$ are independently distributed random variables, and you want to find a vector $v_i = \alpha i + \beta$, where alpha and beta are real numbers, that minimizes the norm of the vector $r_i = X_i - \alpha i - \beta$?If I had to guess, there's no closed form solution for arbitrary X_n. >>11135735Phenomenology of Spirit and Science of Logic, of course. What else?>>11135760>limits of Turing machinesComputability theory?>>11135978Yeah.
 >> Anonymous Mon Nov 11 16:04:24 2019 No.11137597 >>11132976It would mean the power that is directed to or consumed by the pump...kinda self explanatory. If it was talking about energy per unit time imparted to the fluid it would be called hydraulic power.
 >> Anonymous Mon Nov 11 16:45:59 2019 No.11137722 >>11137672Have real roots or only have real roots?
 >> Anonymous Mon Nov 11 17:02:39 2019 No.11137779 >>11137570>What else?https://www.the-philosophy.com/phenomenology-spirit-hegel-summaryI'm reading through this summary but I'm not sure in what part my question is supposed to be treated. I mean, the basic metaphysical notion of the self-aware subject is certainly present, but I think Hegel branches off to psychological questions (collective consciousness etc.) rather than epistemic details concerning existence and essence (this whole curiosity of mine is partially existentially motivated), and I don't suppose he proved any rigorous, system-theoretic theorems. But if there's anything that may be of use to me I'd be grateful if you referred me to the specific chapter/paragraph.>Computability theory?This is what I'm thinking about, and I will look into computability theory. Do the computations in this field also involve information about an aspect of the machine itself? The concept of "measuring a measurement" is obviously infinitely recursive, but measuring external events is not, so where is the line drawn? That's what I have in mind. Thanks for you responses by the way.
 >> Anonymous Mon Nov 11 17:11:17 2019 No.11137807   >>11137672there are lots of polynomials like that. what do you mean by "which"
 >> Anonymous Mon Nov 11 17:32:19 2019 No.11137892 >>11131669>Probably zootopiafagreally makes me think why jannies have more of a problem with me discussing science and engineering in earnest than the latest racebait/incel general/niggers r dum thread
 >> Anonymous Mon Nov 11 18:08:07 2019 No.11137983 >>11137722Only real roots.>>11137807What is the form of those polynomials?I've been trying to find a pattern by looking at sign switches (like using Descartes Rule of Signs) but it's not strong enough.
 >> Anonymous Mon Nov 11 18:36:04 2019 No.11138066 File: 39 KB, 242x170, help.png [View same] [iqdb] [saucenao] [google] [report] Why did the prof write $\delta S$ instead of $dS$? I thought entropy was a state variable? What's the difference between using delta to denote an inexact differential and putting a stroke through the d?https://www.youtube.com/watch?v=JaEqS1ozlHY&t=4205s@ about 30 minutes in
 >> Anonymous Mon Nov 11 18:38:35 2019 No.11138074 >>11138066I didn't even know that $\delta S$ meant something different from $dS$.
 >> Anonymous Mon Nov 11 18:44:39 2019 No.11138087 Mathfag here learning QM. I was pretty on board bra ket notation until I started seeing shit like this[eqn]\mid\Psi\rangle=\int_{-\infty}^{+\infty}\Psi(x)\mid\!x\rangle\mathrm{d}x[/eqn] Wtf is a ket in the integral? What does $\mid x\rangle$ even mean?
 >> Anonymous Mon Nov 11 18:47:20 2019 No.11138096 >>11138074do you know thermodynamics?
 >> Anonymous Mon Nov 11 18:49:40 2019 No.11138105 >>11138096not that well honestly, I did take a thermo class but the professor was total joke
 >> Anonymous Mon Nov 11 18:50:26 2019 No.11138107 >>11138087it's just a column vector, anon
 >> Anonymous Mon Nov 11 18:51:58 2019 No.11138113 File: 1.17 MB, 884x1137, __remilia_scarlet_touhou_drawn_by_yuki_popopo__aa7e67619508fef8151d02ba480cf9a6.png [View same] [iqdb] [saucenao] [google] [report] >>11137983Oof, that's the really hard case. I've got half the classification down, might finish it and post later. Hopefully I'll find some symmetry which lets me turn it into the other one, or I'll start having to appeal to, dare I say it, Newton's formula.>>11137892Not sure what is it you expect from jannies.>>11138066Either the codifferential or the delta physicists use for Lagrangians.
 >> Anonymous Mon Nov 11 18:56:58 2019 No.11138122 >>11138113>Not sure what is it you expect from jannies.I expect them to care whether or not /sci/ related topics are being discussed.
 >> Anonymous Mon Nov 11 19:03:27 2019 No.11138142 >>11138113>Either the codifferentiallooked that up, this is surely not what he is talking about>the delta physicists use for LagrangiansI'm not familiar with that. explain?
 >> Anonymous Mon Nov 11 19:16:21 2019 No.11138172
 >> Anonymous Mon Nov 11 19:56:19 2019 No.11138280 File: 572 KB, 720x1280, line_1573512992810.jpg [View same] [iqdb] [saucenao] [google] [report] I found this in my attic; the fuck am I reading?
 >> Anonymous Mon Nov 11 22:07:00 2019 No.11138520 >>11122775bump
 >> Anonymous Mon Nov 11 22:23:33 2019 No.11138551 Can someone explain to me how the evaluation map of real valued polynomials $R[x]$ has $E_{va}(0)=0$? For example, consider $f(x)=x^2 + 2 \in R[x]$. Then $f(0) = 2$. What am I missing here?
 >> Anonymous Mon Nov 11 22:40:22 2019 No.11138591 How do you study?Seriously, i have 6 subjects (60 credits) to study each semester and everything is being rushed by my shitty professors. I don't see the point of going to lectures given the fact all the lectures are on my student account - 6 hours are wasted everyday i feel. How do you attain all that information in 2 and a half months (only 4 weeks now)? Do you take notes? - i try, but notes just feel like wasting time. It takes me hours to condense shit and it feels like i'm just repeating the lecture slides or textbooks.And then sometimes, i have to learn a concept that just doesn't stick for some reason. Which means i can't go onto the next chapter because you need to know the shit from the previous chapter to move on.Help.
 >> Anonymous Mon Nov 11 22:41:13 2019 No.11138594 >>11138591>60 credits/semesterno you dont
 >> Anonymous Mon Nov 11 23:38:51 2019 No.11138669 File: 32 KB, 553x135, wagner.png [View same] [iqdb] [saucenao] [google] [report] Can someone help me with this? Not really sure what to do here. For a, I assume the average should be 0 mainly because it's a sinusoidal wave, but I don't know how the k values and probability come in to play. I also know that the variance is [x^2] - average^2, so I guess just x^2 if the average is 0. Don't really know how to attempt this, though.
 >> Anonymous Tue Nov 12 02:42:58 2019 No.11138951 >>11138551how is the map defined ?
 >> Anonymous Tue Nov 12 02:54:42 2019 No.11138966 >>11138551The evaluation map maps polynomials to their respective values for fixed elements of the coefficient ring (so $\mathbb{R}$ in this case). In fact it not only maps 0 to 0, it is a ring homomorphism, so it meets the other properties too. But when we say it maps 0 to 0, we don't mean it maps the polynomial evaluated at 0 to the value 0, since the evaluation maps receives polynomials as inputs and not elements of the coefficient ring. What we mean then is that the evaluation map maps the 0 of the polynomial ring (so p(x)=0) to the value 0, for any fixed value of x, which is trivially true.
 >> Anonymous Tue Nov 12 05:18:59 2019 No.11139143 >>11138669Just use cos(a+b)=cos(a)cos(b)-sin(a)sin(b) for a), and plug in manually for b).
 >> Anonymous Tue Nov 12 05:25:49 2019 No.11139152 Any med students or researchers want to tell me why it's been so difficult to cure or at least reduce the impact of cancer? It just seems strange to me that with all the various groups (nonprofits, governments, businesses, etc) and the billions upon billions of dollars spent as well as just the raw number of bright people working on it that we haven't made much progress in the field.Anyone who knows more on the topic care to explain it to me? I know I could totally be missing something.
 >> Anonymous Tue Nov 12 05:42:10 2019 No.11139169 >>11135911Faster Than Light It's a space sim where you are the crew of a ship
 >> Anonymous Tue Nov 12 11:29:18 2019 No.11139684 If f(x)'s limit at a is 0, is the limit of f(x)g(x) also 0 at a for any function g that is defined in the same set as f?
 >> Anonymous Tue Nov 12 11:50:17 2019 No.11139738 >>11139684Nah.Set $f,g : \mathbb{R} - 0 \rightarrow \mathbb{R}$ with $f(x) = x$ and $g(x)=1/x$.>what if I require that they're both defined at the entire real line$f(x)=x$, $g(x)=1/x ~ for ~ x \neq 0, ~ 1 ~ otherwise$.>what if I require g to be bounded and defined on some punctured neighborhood of aThen yes.In fact, in that case, we don't need to even require continuity of g, and if we do, the Weierstrass supremum theorem helps pretty often.
 >> Anonymous Tue Nov 12 12:02:24 2019 No.11139761 >>11139738Thanks for the help!
 >> Anonymous Tue Nov 12 12:07:22 2019 No.11139769 I have a stupid question:►Why are we still on Earth and not in based Moon?
 >> Anonymous Tue Nov 12 12:57:40 2019 No.11139868 File: 127 KB, 768x474, Screen Shot 2019-11-12 at 9.53.38 AM.png [View same] [iqdb] [saucenao] [google] [report] I don't understand this answer. The question is when does $(x+y)^5 = x^5 + y^5$, and I get it ok up until the line below "Substracting this equation from" in pic related. I know that$(x+y)^5 = (x+y)^2(x+y)^2$, but I don't know why I'm supposed to substract $x^3 + y^3 + 2x^2y + 2xy^2$ from it, and I don't really get what proceeds after that. Any tips? the question is from Spivak's calc, chapter 1, problme 16d
 >> Anonymous Tue Nov 12 13:29:50 2019 No.11139964 >>11139868He just subtracted zero, anon.
 >> Anonymous Tue Nov 12 13:30:49 2019 No.11139968   >>11137983what if you look at the factored form: c(z-c1)(z-c2)....(c-cn) ? i think you'd have to have c = +-1 , and each c_i = +-1, so those the roots would also have to be either +- 1.still in most of those cases, the expanded form has coefficients other than +-1, but i think it would be subset of the polynomials whose roots are +-1.
 >> Anonymous Tue Nov 12 13:31:09 2019 No.11139969 >>11139964aw man, lol. at least i posted in the right place, thx =)
 >> Anonymous Tue Nov 12 13:58:07 2019 No.11140025 >>11139964Ok, now I don't understand how $(x + y)^3 = xy(x+y)$ implies that $(x + y) = 0$ or $xy = 0$ in this case. I have no idea how I would've seen that myself or how to justify it.
 >> Anonymous Tue Nov 12 14:33:00 2019 No.11140104 >>11120908What's different between carnivores and herbivores in terms of metabolism? What are the drawbacks of each? Why can't every animal make their own protein from grass?
 >> Anonymous Tue Nov 12 14:58:19 2019 No.11140152 >>11140025>how this implies thatIt doesn't.The xy=0 is from earlier, and he never said (x+y)=0.
 >> Anonymous Tue Nov 12 15:47:53 2019 No.11140260 >>11140152towards the bottom of the screenshot it says "So either x + y = 0 or .." I don't know how that jump was made from (x + y)^3 = xy(x + y). Thanks for replying.
 >> Anonymous Tue Nov 12 15:55:15 2019 No.11140272 >>11140260Ah, right.Essentially, if it isn't zero we can divide out x+y on both sides, and then we get (x+y)^2=xy
 >> Anonymous Tue Nov 12 16:20:00 2019 No.11140336 >>11140260I assume that you understand up to the point:> or x^3+2x^2y+2xy^2+y^3=0right?The next step is rearranging that expression, which is "close" to the expansion of (x+y)^3:(x+y)^3=x^3+3x^2y+3xy^2+y^3=> (x+y)^3-x^2y-xy^2 = x^3+2x^2y+2xy^2+y^3 (subtract x^2y+xy^2 from both sides)=> x^3+2x^2y+2xy^2+y^3 = (x+y)^3-x^2y-xy^2 (swap LHS and RHS)=> x^3+2x^2y+2xy^2+y^3 = (x+y)^3-xy(x+y) (isolate a common factor of xy from x^2y+xy^2)So, the previous assertion:> x^3+2x^2y+2xy^2+y^3=0becomes:(x+y)^3-xy(x+y) = 0=> (x+y)^3 = xy(x+y)This is trivially true if x+y=0 (both sides will be zero), in which case x=-y. Otherwise, x+y is non-zero so we can divide both sides by x+y to get(x+y)^2 = xy=> x^2+2xy+y^2 = xy (expand the square)=> x^2+xy+y^2 = 0 (subtract xy from both sides)Applying the quadratic formula gives y=x(-1±i√3)/2, i.e. the only real solution is x=y=0. Apparently this has already been dealt with in problem 15.
 >> Anonymous Tue Nov 12 17:04:37 2019 No.11140495 >>11140272Oh I see (duh!), thank you that's very simple. >>11140336Thank you as well. This line in particular is where I was lost:>This is trivially true if x+y=0 (both sides will be zero), in which case x=-y. Otherwise, x+y is non-zero so we can divide both sides by x+y to get(x+y)^2 = xy
 >> Anonymous Tue Nov 12 17:37:32 2019 No.11140636 scientifically speaking, what's the best morning routine?
 >> Anonymous Tue Nov 12 17:40:11 2019 No.11140645 >>11140636>wake up>immediately look at your phone>decide to jerk off real quick>then go to the bathroom, brush teeth, shit, etc.>skip breakfast>look at phone and get distracted for a couple more minutes>leave the house late>smoke two cigarettes on the way to work/schoolhaha im just joking haha
 >> Anonymous Tue Nov 12 17:44:22 2019 No.11140661 File: 94 KB, 850x531, __patchouli_knowledge_and_remilia_scarlet_touhou_drawn_by_terimayo__sample-ad96284c916a2e5c6b26afd100f16342.jpg [View same] [iqdb] [saucenao] [google] [report] >>11140636>wake up>turn on light>make alarm stop>have two or three coffees in a row in a state of dizziness while checking your email, fiddling with random objects and thinking about stuff>brush teeth while pissing>dress up and apply deodorant>check if you picked up your keys>leave home
 >> Anonymous Tue Nov 12 17:50:50 2019 No.11140682 File: 166 KB, 334x316, bun4.png [View same] [iqdb] [saucenao] [google] [report] >>11140661why is that touhou holding kafka's metamorphosis?
 >> Anonymous Tue Nov 12 20:46:27 2019 No.11141224 File: 39 KB, 804x135, 1Mid1sh.png [View same] [iqdb] [saucenao] [google] [report] asking on SQT because I probably did a stupid proof.We know that there exists an N such that if b >N, then |int_1^b g(x)- A| < epsilon for some A. Since g > |f|, we also know that if b > N then |int_1^b f(x) - A| < epsilon.this feels incorrect, can someone guide me
 >> Anonymous Tue Nov 12 20:55:55 2019 No.11141251 File: 3.22 MB, 2507x3541, __flandre_scarlet_and_remilia_scarlet_touhou_drawn_by_yada_xxxadaman__dec0bcc6afe68c7527007ab4127ebad4.png [View same] [iqdb] [saucenao] [google] [report] >>11140682Great eyes.Like a bunny.>>11141224Does R mean something like "locally integrable functions" or "measurable functions"?Because if it does, you just need to partition R (the real line) by the naturals, split up the integral from one to infinity into the sum of those integrals from one integer to the next, and then bound the infinite series by the similar infinite series associated to g, and show it converges by the trivial argument.Your argument is nonsense, to be entirely honest.
 >> Anonymous Tue Nov 12 21:01:07 2019 No.11141261 >>11141251It means Riemann integrable functions
 >> Anonymous Tue Nov 12 21:04:55 2019 No.11141271 >>11141224You can tell your argument is wrong because the value of the integral of g(x) may be very different from the value of the integral of f(x) and even |f(x)|. I'd approach it like this: By absolute convergence (which we can prove by cauchy criterion) we instead prove that $\int_1^{\infty} |f(x)| dx$ exists and converges.We define $F(x) = \int_1^{x} |f(t)| dx$. It is clear that F(x) is monotone (i.e. it is increasing) and it is also bounded by $\int_1^{\infty} g(x) dx$. Hence $\lim_{x \to \infty} F(x)$ exists.
 >> Anonymous Tue Nov 12 21:10:06 2019 No.11141282 >>11141271There's a theorem in baby Rudin (6.12) that says if f1 < f2 on [a,b], then int_a^b f1 dx <= int_a^b f2dxWhy wouldn't it apply here (since for any b, f < g on [1, b] so the integral is also less)?
 >> Anonymous Tue Nov 12 21:13:20 2019 No.11141290 >>11141282It is less but when you say>|int_1^b f(x) - A| < epsilon.notice that you are implying that the integral will converge to A. But that can't be because if a certain g(x) works, then so does g(x) +1, and g(x) + 2. Can't have 3 different limits, johnny boy.
 >> Anonymous Tue Nov 12 21:15:23 2019 No.11141294 >>11141251Fuck, I forgot about muh deviations within the partition.You can correct it by considering that g needs to decrease really fast, tho.>>11141271Also works, but depends on the theorems you have on hand.>>11141282Because no.
 >> Anonymous Tue Nov 12 21:20:10 2019 No.11141307 >>11141290I fucked this one up. If a certain g(x) works, so does 2g(x) and 3g(x) and so on. Not g(x) +1 because improper, small brain.
 >> Anonymous Tue Nov 12 21:22:07 2019 No.11141309 >>11141290>>11141294sorry I think I'm just slow in the head, I'm not trying to challenge you or anything I think my proof is also wrong but I'm just having a hard time understanding where I went wrong, since the int_1^b f(x) < int_1^b g(x), andsince |int_1^b g(x) - A| < epsilon, then int_1^b g(x) < epsilon + Aso int_1^b f(x) < epsilon + A, but I guess the reason why this proof doesn't work is because we don't know that -epsilon + A < int_1^b f(x) so we can't conclude anything.I hate analysis so much, I think I just want to stick to smaller brain math like combinatorics
 >> Anonymous Tue Nov 12 21:24:54 2019 No.11141315 >>11141309The mistake is in the third line. In particular, you can swap the inequality around since the integral is always smaller than A.
 >> Anonymous Tue Nov 12 21:26:58 2019 No.11141323 >>11141315>swap the inequality aroundMy bad, I'm slowly going insane.
 >> Anonymous Tue Nov 12 21:39:43 2019 No.11141347 >>11141224This is just the Comparison Test for improper integrals, right?
 >> Anonymous Tue Nov 12 21:43:14 2019 No.11141352   File: 95 KB, 923x924, 71267238_469926987064280_715848843643154787_n.jpg [View same] [iqdb] [saucenao] [google] [report] Does anyone have a __They Live__ shop of this picture?
 >> Anonymous Tue Nov 12 21:44:11 2019 No.11141354 >>11141352>>>/pol/I remember you starting that thread a couple days ago. Fuck off.
 >> Anonymous Tue Nov 12 21:49:40 2019 No.11141368 >>11141354Given that they only finished the mural yesterday, I doubt that.
 >> Anonymous Tue Nov 12 21:57:52 2019 No.11141376 >>11141368Nah, I'm not mistaken. It was some gay bullshit like>hey /sci/, is there any way we can fuck this up?with a picture of the unfinished mural
 >> Anonymous Tue Nov 12 22:18:26 2019 No.11141419 >>11141376I saw the unfinished mural and though that it had a very fascist aesthetic, so I decided to ask here. It is more /pol/, but it is tangentially related to /sci/, and I thought maybe someone here would deliver.
 >> Anonymous Tue Nov 12 23:20:16 2019 No.11141571 When I put 2 into prime factor calculators it gives me the answer of either "2" or "2*1". What's up with that? Surely both answers are wrong.
 >> Anonymous Tue Nov 12 23:25:45 2019 No.11141588 >>11141571i mean 2*1 is technically wrong since 1 isn't a prime and if it were considered as one then the prime decomposition of any number would not be unique, unless for whatever reason their * stands for ^ and they mean 2^1 which i guess would be a more complete answerbut what problem do you see with just 2? what answer were you expecting to begin with?
 >> Anonymous Tue Nov 12 23:31:40 2019 No.11141604 >>11141419>fascist aesthetic Sounds right up your alley then. Go back to your containment board, fag.
 >> Anonymous Wed Nov 13 00:26:40 2019 No.11141825 >>11141604Not really. Her fundamental thesis is that we shouldn't involve and engage the stakeholders in society who currently propagate our fossil fuel economy; that coming to a compromise between equals for how to move on from our current situation is "childish". Her message is one of fascist and authoritarian action. Maybe you are confused about who is the Nazi?
 >> Anonymous Wed Nov 13 00:29:50 2019 No.11141837 >>11141825>Her message is one of fascist and authoritarian actionSounds right up your alley then. Go back to your containment board, fag.
 >> Anonymous Wed Nov 13 00:41:21 2019 No.11141891 >>11141837You keep using that word. I don't think it means what you think it means.
 >> Anonymous Wed Nov 13 00:43:43 2019 No.11141901 File: 24 KB, 400x382, 1500361938377.jpg [View same] [iqdb] [saucenao] [google] [report] >>11141891You see this? It means "NOT WELCOME." Back to your shithole.
 >> Anonymous Wed Nov 13 01:20:02 2019 No.11142078 I can program, but struggle finding motivation to do so. I have fun doing Project Euler type problems and I’ve been leafing though this competitive programming book: https://cses.fi/book/book.pdf, but this stuff feels superfluous.I guess what I’m getting at is that I want to program recreationally but don’t quite know how to do so in a manner I enjoy. Any “real project” is either unwieldy in its tedium or its already been done before, and better.I downloaded Turtle Geometry and The Algorithmic Beauty of Plants in hopes of that interest taking off. Maybe I’d enjoy making a little game using finite automata and L-systems, or something. Any ideas would be appreciated.
 >> Anonymous Wed Nov 13 01:24:24 2019 No.11142098 So in relation to the above, in case it wasn’t clear: any fun /sci/ or /mg/ approved programming ideas would be cool.
 >> Anonymous Wed Nov 13 01:29:00 2019 No.11142113 >>11142078I'm really bad at coming up with small projects that feel worthwhile but if you want a problem set the Rosalind bioinformatics ones are pretty good.
 >> Anonymous Wed Nov 13 02:49:57 2019 No.11142285 >>11141588>what answer were you expecting to begin with?Good point, I retract my question
 >> Anonymous Wed Nov 13 03:22:26 2019 No.11142326 Would you refer to the set 4,9,25,49,121 etc as prime squares? The numbers themselves aren't prime but they are prime numbers squared. Not sure what to call them
 >> Anonymous Wed Nov 13 03:26:26 2019 No.11142336 >>11142326I would call them squared primes
 >> Anonymous Wed Nov 13 05:36:27 2019 No.11142518 >>11142326squares of primes
 >> Anonymous Wed Nov 13 07:51:26 2019 No.11142643 >>11140104Anyone?
 >> Anonymous Wed Nov 13 08:50:55 2019 No.11142711 how do you prove that $\frac{dt}{dt'}=1-\hat{n}\cdot\vec{\beta}$? what does it even mean?
 >> Anonymous Wed Nov 13 09:51:50 2019 No.11142792 >>11140104Cellulose is really hard to digest, so herbivores have strategies including multiple stomachs, chewing the cud (regurgitating partially digested food, chewing it, then swallowing it again), and/or coprophagy (eating faeces of partially-digested food).This leaves a niche for predators to feed on all that ready-processed food walking around. But obviously you can't have an ecosystem with nothing but predators; something has to be at the bottom of the food chain.You could theoretically have an ecosystem with nothing but herbivores. But they won't live forever, so something may as well put the carrion to use. And from there, there's no particular need to wait for the herbivores to die naturally before eating them.
 >> Anonymous Wed Nov 13 12:59:53 2019 No.11143205   File: 4 KB, 343x182, mpfrtrfrpfprtrfrsmalamasamampfrtffffffffsniffitgoddamnsniffitdmspspsdsds.png [View same] [iqdb] [saucenao] [google] [report] assume this is a slingshot, so you're pulling at the top of the triangle. g = 6cm, so we've got that s = sqrt(h^2+9). i want to find an expression for ds/dt in terms of dh/dt and h. I use ds/dt = ds/dh * dh/dt and end up with ds/dt = h/(sqrt(h^2+9)) * dh/dt. i'm given that h rises with a speed of 2 cm/min. now, assuming that the height has reached 11 cm, i find that s is growing by 1.93 cm. does that sound right? sounds like a lot to me desu.
 >> Anonymous Wed Nov 13 13:29:42 2019 No.11143246 Ok boys, new question: at what temperature (high, low is easy google) are nerves permanently damaged? If using heat as a method of torture, what would be the maximum temperature used before nerve damage lessened the sense of pain.
 >> Anonymous Wed Nov 13 14:13:51 2019 No.11143331 >>11143205sounds right to me
 >> Anonymous Wed Nov 13 14:25:38 2019 No.11143349 >>11142711Looks like nonesense, but I could be wrong.
 >> Anonymous Wed Nov 13 15:26:31 2019 No.11143478 >>11142711I'm guessing this is proper time?
 >> Anonymous Wed Nov 13 15:27:55 2019 No.11143480 Does L'Hospital's rule apply in complex analysis? Like can you show that $\lim\limits_{z\to0}\frac{\sin z}{z}=1$ by L'Hospital's? I know the preferred way is by using power series, but I was just curious if L'Hospital's still applies.
 >> Anonymous Wed Nov 13 15:32:12 2019 No.11143491 >>11141307>>11141309>small brain>brainlet>apologizing unnecessarily for not conveying information properly on a nazi-pedophile-weeb forumYou all need to stop doing this. We already know you're stupid, announcing this only makes you a target for midwits to attempt opportunistic cruelty towards you
 >> Anonymous Wed Nov 13 15:49:37 2019 No.11143541 What stats courses should I take for physics? Read, "should," I get that stats isn't usually required for physics majors for a reason, but I want to know what stats knowledge you guys have found useful since I have space for quite a few electives
 >> Anonymous Wed Nov 13 16:11:06 2019 No.11143595 What are the benefits of blood donations (I'm counting here normal donation, plasma and platelet donation)? My family keeps asking retarded questions on why I donate when I could simply not, but the only thing I've noticed is that I have lower blood pressure for some time after.
 >> Anonymous Wed Nov 13 16:30:52 2019 No.11143639 >>11143595In some countries after 10 blood donations you are exempt from paying for certain medical services.Other benefit is that you will help someone who is in dire need for blood transfusion.
 >> Anonymous Wed Nov 13 16:33:02 2019 No.11143645 >>11143541read a book on probability and measure instead of wasting months of your life in a stats class filled with brainlets. you can and should self teach probability theory, its very useful for stat mech and qm
 >> Anonymous Wed Nov 13 16:37:17 2019 No.11143659 >>11143639I would argue there is no true altruism here. Everyone is doing it for some selfish reason - making yourself feel better knowing you helped someone, payment, other bodily benefits among other things. We don't have any exemptions like you mentioned, but I did read that if we need some service like a transplant, previous donors have priority. But still, I was hoping for more immediate personal benefits - I did read that blood donors have lower levels of cholesterol and live longer on average, but causality is not clear on this one
 >> Anonymous Wed Nov 13 16:51:54 2019 No.11143713 >>11129201>Particle physics questionthis is not a particle physics question> Suppose an oxygen atom is moving at a constant velocity through space. It passes by another oxygen atom, and immediately binds with it. Does it slow down correspondingly?If the other atom is at rest, then by conservation of momentum the combined atom will slow down. Is that what you ask?
 >> Anonymous Wed Nov 13 16:57:47 2019 No.11143732   http://tutorial.math.lamar.edu/Solutions/CalcI/SubstitutionRuleDefinite/Prob2.aspxhow did this nigga go from 8/10 to 8/5... bruh da fuck.....
 >> Anonymous Wed Nov 13 17:16:16 2019 No.11143785 File: 5 KB, 232x119, fads.png [View same] [iqdb] [saucenao] [google] [report] why doesn't [[ebx]] work and i have to do it this way around?(i need to decrement the value that's under the address stored in memory to which i have address)
 >> Anonymous Wed Nov 13 17:27:12 2019 No.11143808 >>11143785I think you could dosub [eax], 1instead ofmov ebx, [eax]sub ebx, 1mov [eax]. ebx[[ebx]] doesn't work because there is no processor opcode that does a double dereference like that.
 >> Anonymous Wed Nov 13 17:55:12 2019 No.11143879 >>11143808ah thanks, the more i do in assembler the more annoying it gets
 >> Anonymous Wed Nov 13 19:39:06 2019 No.11144268 >>11143645I see, I should've figured anyways since most of the stats I've used so far has been error propagation, and obviously I learned it from Taylor's book. Thanks anon
 >> Anonymous Wed Nov 13 19:45:50 2019 No.11144287 Is it correct to say that a projective module is a module P such that every morphism onto it from any module has an inverse on the right that is also a morphism?I'm trying to understand what a projective module is and why it's useful or important. I know the "lifting" definition but I don't get what it's trying to say, and I'm trying to work with its characterizations instead. For example I've seen projective modules be referred to as locally free modules, but I also don't get what's that's supposed mean since having a basis locally doesn't really seem to make too much sense, and I haven't seen someone define that property instead of just mention it (any textbook I should read that has that definition, by the way?). I've also seen the short split sequence "definition" (which we learned as a theorem), that states that a module P is projective iff every short exact sequence $0 \longrightarrow A \longrightarrow B \longrightarrow P \longrightarrow 0$ is split. Now, among all the characterizations of short split sequences, I remember that a short sequence is split iff the morphism from B to P has an inverse morphism to the right, and since that's supposed to happen for any module B, that's where I get my "definition" in the first paragraph, where I try to drop the context of short exact sequences and just mention surjective morphisms in general. Is this idea good enough, then? Also anyone has a better way to understand the idea of projective modules?
 >> Anonymous Wed Nov 13 20:06:10 2019 No.11144355 >>11143879Just write a preprocessor that translates your N-indirection into the appropriate instructions and then run it through the assembler.
 >> Anonymous Wed Nov 13 20:49:55 2019 No.11144485 >>11143480Yeah, just power expand the numerator and the denominator around the point you want to evaluate (in other words, you pretend the point is 0) and cancel out x^n s. The remainder of nonconstant terms vanish.
 >> Anonymous Wed Nov 13 20:56:25 2019 No.11144503
 >> Anonymous Wed Nov 13 23:58:25 2019 No.11144893 File: 35 KB, 738x550, SumatraPDF_2019-11-13_23-56-50.png [View same] [iqdb] [saucenao] [google] [report] >>11120908can somebody solve it step-by-step?
 >> Anonymous Thu Nov 14 00:42:10 2019 No.11145003 File: 46 KB, 738x550, 1573707505797.png [View same] [iqdb] [saucenao] [google] [report] >>11144893complete the drawing so you have more friendly shapes like triangles and quadrilaterals instead of that weird thingwork out the angles from the bottom and the top to the middle quadrilateral, using stuff like supplementary angles and the suchand i think you can finish it finding with the middle quadrilateral
 >> Anonymous Thu Nov 14 00:48:47 2019 No.11145022 >>11144503that's what you get when you try and find the antiderivative of an arbitrary function.
 >> Anonymous Thu Nov 14 02:31:05 2019 No.11145316 I'd like some help with one of my practice paper.Consider functions from a set with 5 elements to a set with 3 elements. How many of them are surjective?My logic is as follows:Since we want to partition the domain into 3, there are (7C2) ways of doing so. this multiplied by the number of ways for it to be matched with the codomain 3! Thus my answer is (7C2) * 3! = 126, which is different from the correct answer (150). Can someone point out my error?
 >> Anonymous Thu Nov 14 02:31:12 2019 No.11145317 File: 1021 KB, 500x374, 1565952029924.gif [View same] [iqdb] [saucenao] [google] [report] >>11120908What's the tern that describes the condition where one point continuously approaches another stationary point for infinity? Such as in the case of repeatedly halving a number forever with respect to zero.
 >> Anonymous Thu Nov 14 02:42:50 2019 No.11145332 File: 43 KB, 1029x100, lZfIhJU.png [View same] [iqdb] [saucenao] [google] [report] anyone know how to go about this?
 >> Anonymous Thu Nov 14 02:45:29 2019 No.11145335 File: 69 KB, 480x1349, FF23.jpg [View same] [iqdb] [saucenao] [google] [report] >>11145003This problem has me thinking about the general case where 60 is a function of θ which I have labelled as y. I feel like there is some three dimensional solution to this. Maybe if the red/blue line was a flag pole or something, purple being a shadow from some source.
 >> Anonymous Thu Nov 14 03:45:38 2019 No.11145403 File: 13 KB, 485x411, why.png [View same] [iqdb] [saucenao] [google] [report] Why are these two functions the same?
 >> Anonymous Thu Nov 14 04:00:25 2019 No.11145420 >>11145332Anon I...
 >> Anonymous Thu Nov 14 04:11:56 2019 No.11145442 >>11145420I'm sorry.
 >> Anonymous Thu Nov 14 04:13:56 2019 No.11145447 >>11145403what's the value of floor(x) between x=n and x=n+1?
 >> Anonymous Thu Nov 14 04:19:56 2019 No.11145461
 >> Anonymous Thu Nov 14 04:23:45 2019 No.11145472 Alright, I have a silly question. What's the most energy-efficient way to turn elemental lead into not lead? Doesn't have to be gold, per se, but ideally anything else that isn't so toxic to humans?
 >> Anonymous Thu Nov 14 05:00:44 2019 No.11145510 File: 19 KB, 644x154, Capture.png [View same] [iqdb] [saucenao] [google] [report] >>11120908Good-day.Been doing numerous integration by susbtitution questions and whilst I am getting to grips with it, I am not sure how to do the latter question. Are you supposed to let u = e^t^3 then differentiate and rearrange for t? I am not sure if the ^3 cancels the e so it'd be just t or any other way of differentiating it.
 >> Anonymous Thu Nov 14 05:01:17 2019 No.11145513 Several pharmaceutical companies have developed and market specific inhibitors or therapeutic monoclonal antibodies to inhibit the activity of a ReceptX transmembrane receptor. This receptor has tyrosine kinase activity.In their MA, the indications for these drugs specify that they can only be prescribed for lung cancer when the tumour overexpresses this receptor.No company currently offers the pulmo-Test, an in vitro diagnostic test capable of detecting overexpression of the ReceptX receptor, in lung cancer. Your R&D team wishes to develop a strategy to occupy this market sector of the Medical Diagnostics industry.Make different (motivated) proposals to your management, detailing the stages of development (design), validation, (performance verification) of your tool. The commercial approach (marketing for whom? in what form? ease of use etc...) must be specified.Someone has some ideas?
 >> Anonymous Thu Nov 14 05:28:05 2019 No.11145549 >>11145510sub t^3, look at the numeric value given in the answer and the limits of integration
 >> Anonymous Thu Nov 14 06:17:37 2019 No.11145602 File: 1.47 MB, 1906x2149, Comfy.gif [View same] [iqdb] [saucenao] [google] [report] >>11145549I got the answer, thank-you very much!~
 >> Anonymous Thu Nov 14 12:01:44 2019 No.11146195 https://www.youtube.com/watch?v=XyB0ntATMXY&feature=youtu.be&fbclid=IwAR23bybkqwmaPdCvD9VA0rWi46YuUuo_oHDRikspJol9cuiaq7a0Jofi8aQThe Earth really is flat, isn't it? Oh fuck.
 >> Anonymous Thu Nov 14 12:26:04 2019 No.11146254 >>11142113thanks, and also bumping my original question
 >> Anonymous Thu Nov 14 12:54:39 2019 No.11146319 Rather than retyping my problem, I'm going to post an exact replica I found on physics forums (the poster descrubes my exact thought process and exactly where I'm stuck):Like a huge faggot, he left the thread by saying he figured it out, basically, and did not fill in future readers. But in particular I am confused by the line he mentions:>then our formula isn't actually $b2−4c<0$ but $b2/a−4c/a<0$
 >> Anonymous Thu Nov 14 12:56:37 2019 No.11146326 File: 65 KB, 1050x1050, Zeno_Achilles_Paradox[1].png [View same] [iqdb] [saucenao] [google] [report] >>11145317Not sure what term you're looking for, but you're probably thinking of Achilles and the tortoise paradox
 >> Anonymous Thu Nov 14 13:14:36 2019 No.11146365 what's the healthiest way to use nicotine? i definately notice the brain gains when I'm on it
 >> Anonymous Thu Nov 14 13:32:14 2019 No.11146413 File: 137 KB, 1003x323, Screen Shot 2019-11-14 at 10.19.31 AM.png [View same] [iqdb] [saucenao] [google] [report] >>11146319Pic related is the problem. I just do NOT understand how the first term is squared. I can only arrive at the same solution but with only the numerator squared, not the denominator. It's just a complete the square problem, so I get:$\frac{b^2}{a} - \frac{4c}/{a}$, I don't know how I'm supposed to get (b/a)^2.
 >> Anonymous Thu Nov 14 13:52:23 2019 No.11146465 >>11146413ok, i think i get it, but I'm not sure why the author would do it this way. why hault the algebra at $a(x+\frac{b}{2a})^2 + \frac{c}{a} - \frac{b^2}{4a^2} < 0$? from here I can see how to get $(\frac{b}{a})^2 - \frac{4c}{a} < 0$, but like why not distribute the $a$ first in the above to get $a(x+\frac{b}{2a})^2 + c - \frac{b^2}{4a}$, and then get the inequality $\frac{b^2}{a} - \frac{4c} < 0/math]?  >> Anonymous Thu Nov 14 13:54:39 2019 No.11146478 >>11146465fuck, sorry bout the tex:>and then get the inequality [math] \frac{b^2}{a} - \frac{4c} < 0$?also, this:>$a(x+\frac{b}{2a})^2+\frac{c}{a}−\frac{b^2}{4a^2}<0$? was supposed to be>>$a[(x+\frac{b}{2a})^2+\frac{c}{a}−\frac{b^2}{4a^2}]<0$? >
 >> Anonymous Thu Nov 14 18:04:34 2019 No.11147161
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