/sqt/ /qtddtot/ - stupid questions thread

[Anonymous No.11268274]

previously >>11250238

Happy New Year~

[Anonymous No.11268279]

Happy new year, I'm retarded so, can I become immortal by giving every cell in my body cancer somehow?

[Anonymous No.11268301]

~UNANSWERED QUESTIONS~

Math:
>>11250403
>>11255167
>>11261111
>>11265225
>>11268140

Physics and astronomy:
>>11250879
>>11262177
>>11267657 (yes. relativity isn't relevant.)

Chemistry:
>>11259057 (it does rust in nature)
>>11261572

Biology and physiology:
>>11262564
>>11265156

Psychology:
>>11257905 (sleep is very good for you. but why?)

Stupid:
>>11251585
>>11260593 (same)

My drunk ass probably missed something.

[Anonymous No.11268308]

>>11257905
hypomania, its not good for you. learn to function properly with normal sleep or suffer the consequences.

[Anonymous No.11268317]

>>11268279
no

[Anonymous No.11268799]

Hey can anybody download a book from libgen these last 2 days? Whatever download link I click on it just gives me html file to that very download page. WTF?

[Anonymous No.11268846]

i have a pain that shoots from my tailbone to my dick and balls especially when i bend over or deadlift, is it a disk hernia or is it something related to my prostate?

[Anonymous No.11268862]

>>11268799
Specifically libgen.pw

[Anonymous No.11268980]

I've googled it and I still can't understand what the eigenvalues of a matrix are. What are they and what's their utility?

[Anonymous No.11268988]

>>11267657
Just use Kepler's law
[math](M1 + M2) = \frac{a^3}{T^2}[/math]

[Anonymous No.11268998]

>>11268980
in physical systems, a quick way to tell if the system is stable.
if eigenvalues are negative, the system damps out to nothing.
if they are positive, the system will blow up over time.

[Anonymous No.11269000]

>>11268980
https://youtu.be/PFDu9oVAE-g

[Anonymous No.11269049]

>>11268862
>>11268799
I haven't tried libgen.pw, but it works fine for me.

[Anonymous No.11269052]

>>11268988
That’s not true tho

[Anonymous No.11269057]

>>11269049
well gen.lib.rus.ec works for me as always but I think it has a different library.

[Anonymous No.11269060]

>>11269052
What are you talking about?
http://hosting.astro.cornell.edu/academics/courses/astro201/kepler_binary.htm

[Anonymous No.11269079]

Is there a name for this shape?

[Anonymous No.11269088]

>>11269052
Anon missed a constant of proportionality, but yes it is true.
[eqn] M_1+M_2=\frac{4\pi^2a^3}{GT^2}=\frac{4\pi^2(2.992\times10^{12})^3}{(6.673\times10^{-11})(1.261\times10^9)^2}=9.965\times10^{30}\ \text{kg}=\text{total mass} [/eqn]

[Anonymous No.11269101]

>>11269079
"doubly faced cylinder"

[Anonymous No.11269126]

>>11269088
I didn't miss a constant of proportionality, the constant of proportionality is 1 in that form, as it just gives the answer in solar masses.

[math]\displaystyle (M_1 + M_2) = \frac{(20 AU)^3}{(40y)^2} = 5M_{\odot} = 5 \cdot 2 \times 10^{30} kg = 10 \times 10^{30}kg[/math]

because
[math]\displaystyle M_{\odot} = \frac{4\pi^2 (AU)^3}{G \cdot y^2}[/math]

[Anonymous No.11269286]

how can I develop new senses

[Anonymous No.11269629]

>>11268846
It's either a pinched nerve or inguinal hernia; prostate problems won't just happen when you DL. Go see a physio.

[Anonymous No.11269647]

Will 2020-2029 suck as much as 2010-2019?

[Anonymous No.11269685]

How do I make myself have more vivid dreams?

[Anonymous No.11269795]

I have an interview at a company for a position I never applied for nor do I know what the position is. I just met them and gave them a resume a few months back, not necessarily applying for anything specific.
What the fuck should I study for? I'm guessing this is a basic electrical engineering position? I'm about to become a senior in EE.

[Anonymous No.11269828]

>>11269428
>Splits [math]\mathbb{R}[/math] into a partition with more elements than [math]\mathbb{R}[/math]
Checkmate atheists.

http://karagila.org/2014/anti-anti-banach-tarski-arguments/

[Anonymous No.11269883]

Anyone have any good video lectures/video essays/reading material about eternalism, proofs for and against, whether or not it has any relation to mathematics/physics

>>11269647
Yes

>>11269685
Stop smoking weed/cigaretts, time your sleep to line up with REM, there's certain vitamins and plants you can take that increase brain activity in sleep.

>>11269795
Is an EE just the guy that takes the idea and turns it into a blueprint? I don't know about the actual process of that but I've done blueprints before, git gud at math, memorize the national code, basic engineering knowledge and common sense also go a long way.

[Anonymous No.11269961]

how much is a lot of money? what is the ideal amount to have in a savings account?

[Anonymous No.11270039]

>>11269079
Energy Dome.

[Anonymous No.11270058]

>>11269685
eat tons of pizza then go to sleep

[Anonymous No.11270075]

What depth of knowledge would be necessary to be considered classically educated in math, chem physics?

[Anonymous No.11270079]

>>11269961
>how much is a lot of money?
depends on your definition
>what is the ideal amount to have in a savings account?
at least 6 months of vital expenses (rent/mortgage, utilities, food, etc) in a high yield savings account.

[Anonymous No.11270142]

On a Vitali set, since we end up with [math]1 \leq \mu(S) \leq 3[/math]

Is there some kind of trick that could be done to give a finite answer if it was possible that [math]\mu(S) > 0[/math] ? Like with [math]\zeta[/math] regularization or something else?

[Anonymous No.11270295]

>>11270142
Regularizing [math]\mu(S) = \sum_k \mu(V)[/math] amounts to regularizing infinite sums of constants, which comes down to evaluating [math]\mu(V)\zeta(0) = -\frac{1}{2}\mu(V)[/math]. Now since the analytic continuation of the generalized [math]\zeta[/math] is regular, other regularization schemes such as Borel would give the same answer.

[Anonymous No.11270501]

>>11270295
Ah, so that's how it goes, thanks.
>other regularization schemes such as Borel would give the same answer.
How about the dirichlet method here:
https://math.stackexchange.com/questions/2619740/zeta-regularization-vs-dirichlet-series

As he says the dirichlet continuation there isn't compatible with [math]\zeta[/math] regularization.

[Anonymous No.11270531]

>>11270501
Ah yeah I've seen something like this, but it seems to me to be merely a choice of the "basis", so to speak, of the regularization scheme. The reason I say this is because Feynman amplitudes in [math]\phi^4[/math], for instance, has been proven by Brown to be linear combinations of multi-zeta values below order [math]8[/math] (as in the [math]\eta[/math]-reg). On the other hand, there is also the Connes-Kreimer result which expresses dim-reg as a choice of a section of the principal [math]\mathbb{G}[/math]-bundle over the punctured disc [math]D = \{d\in \mathbb{C}\mid |4-d| \leq 1\}[/math], where [math]\mathbb{G}[/math] is some cosmic motivic Galois group acting on the Hopf algebra of Feynman graphs. I'm not clear about the details, but I believe difference choices of reg-schemes correspond to a difference choice of such a section.

[Anonymous No.11270928]

what's the science behind the golden ratio

[Anonymous No.11271011]

How quickly does bronze go green?
I want to draw a greek character with armor of the time but I'm not sure what color it should be.
Did it last a long time looking pristine? Did it oxidize quickly, and they wore it with green patches?

[Anonymous No.11271072]

>>11268301
>god I wish flandre were my girlfriend
>a question
Boy, were you drunk.
>>11250403
>what is linear regression
>>11265156
Is this about sex reassignment?
I'm sure it would be easier to just google "do you have to dilate forever" or something;
>>11269079
Urysohn's lemma's proof's shape.

[Anonymous No.11271130]

>>11271072
>maxima
Huh, didn't notice.
Let me see if I find anything.

[Anonymous No.11271133]

>>11271011
That shit takes years to form and only if left to be in nature.
A soldier of the time would polish his armor and keep it shiny golden, can't imagine it ever going green during service.

[Anonymous No.11271138]

>>11271130
Right, right. Found absolutely nothing, so here's what I would do:
Option one:
Literally just plug it into software (i.e. Wolfram) as is.
Option two: at k, the second largest error necessarily equals the largest error. Otherwise, we could disturb k such that we reduce the largest error, and the second largest would still be smaller than it. Assuming, of course, that you've already removed the null b_i.
So you tell your computer to consider the finite set of problems of the form "find k such that these two have equal modulus", where these two go through all possible combinations, and then you pick the one with smallest overall error.

[Anonymous No.11271284]

Im trying to do a thing with the libre office version of excel and dont know how to do it (either in excel or libre office)

I want to average the value between two cells, but only if both cells contain a non zero value.

What I have are a bunch of partially overlapping data sets, and I need to combine them together. So I want to average them where they overlap, otherwise just take the value that isnt 0. Is there an easy way to do this in excel, or do I need to write a python script for this or something?

[Anonymous No.11271324]

>>11250879
>>11268274

A nebula is a precursor to a galaxy, and in a way you might consider a galaxy to be a nebula with stars in it, but generally it would be considered a totally different kind of structure. A nebula is just a large collection of gas and dust that may or may not be in the process of forming stars. A galaxy is much more structured usually, and while it still does contain some loose gas and dust, it is much more diffuse than in a nebula. Nebula can also contain some stars, but not necessarily. There are also planetary nebula, which is the same idea but on the scale of a single star system. They eventually condense into a solar system. Galaxies are predominantly made out of stars, the finished product, while nebula are predominantly made of gas and dust, the raw materials.

[Anonymous No.11271493]

Is it true that if [K:Q] = 2^m, m>1, then K intersect R is nontrivial (larger than Q)?
Q here is the set of rational numbers.

[Anonymous No.11271544]

>>11271493
I think so. The extension has finite degree, so it's algebraic.
We choose an appropriate base for K over Q. One of its elements is the unity, the remainder need to be closed under conjugates, since the polynomial still zeroes. But we can't have a conjugation map for 2^n-1 non-real elements.

[Anonymous No.11271560]

>>11271544
Why not? Think about Q[i]
A basis is {1, i}. How does your argument not work in this case?

[Anonymous No.11271571]

>>11271560
Because i's conjugate is itself.
The argument gets stuck exactly at
>But we can't have a conjugation map for 2^n-1 non-real elements.
And I did consider the possibility, but I assumed you'd have issues having a purely imaginary number and other complex roots, and then a real root could be dragged out.
For example, if it has [math]\sqrt{-2}[/math] and i, you can do division to find a non-trivial intersection, namely [math]\sqrt{2}[/math].

I don't really want to come up with some algorithm to do this, desu, sounds like a pain.

[Anonymous No.11271575]

>>11271571
>Because i's conjugate is itself.
i's conjugate is the other root of x^2 + 1, which is -i. -i != i.l

[Anonymous No.11271581]

>>11271575
I know anon, I'm half asleep.
I meant "i's conjugate is in the same subspace, so it doesn't affect the basis."

[Anonymous No.11271607]

>>11271581
So assume we have a purely imaginary root [math]ai[/math], a some real number, and a second complex non-imaginary root z. Since [math]\overline{z}[/math] is also a root of whatever equation z satisfies, we also have [math]\overline{z}[/math].
[math]Re(z)=\frac{z}{2}+\frac{ \overline{z}}{2}[/math] is either a rational number q or we're done.
If it isn't, we take [math]w=z-q[/math], where w is clearly imaginary, and then [math]w/ai[/math] is real, concluding the proof.

[Anonymous No.11271613]

>>11271607
Yeah that's easy. And what if we dont have a purely imaginary root?

[Anonymous No.11271615]

>>11271613
Then we have the issue with the conjugation map explained in my first post.

[Anonymous No.11271776]

>>11268988
of ffs im an idiot, I thought it meant the masses of the individual stars, not the combined mass of the stars, so i got there and couldnt go further. Cheers Anon!

[Anonymous No.11271868]

Yo is this shit accurate https://www.youtube.com/watch?v=JYAq-7sOzXQ

[Anonymous No.11271891]

Why do you call Xanthine "3,7-Dihydro-1H-purin-2,6-dion" and not "1,3,7-Trihydro-purin-2,6-dion"? Why is the H in 1-position special?

[Anonymous No.11272300]

Suppose I have quadratic optimization problem with quadratic constraints, is there a way to know how many local minima are there?

[Anonymous No.11272313]

>>11271891
"hurr durr I know long formulas" go back to fucking reddit

[Anonymous No.11272339]

>>11272300
>the exact number
I doubt it, to be honest.
What you might be able to do is apply intersection theory to compute upper bounds on the number of critical points.

[Anonymous No.11272395]

>>11272300
Suppose the polynomial that gives the restriction is [math]p(x)[/math] and the polynomial we want to minimize is [math]q(x)[/math].
A critical point of [math]q(x)[/math] in the hypersurface [math]p(x)=0[/math] satisfies [math]grad ~ q(x) = \lambda n[/math], where [math]n[/mat] is a vector normal to the hypersurface and [math]\lambda[/math] is some real number, possibly zero.
I might be completely fucking wrong, but I think that [math]grad ~ p(x)[/math] was normal to [math]p(x)=0[/math].
So the actual critical points are [math]C = \{ x \in \mathbb{R}^n ~ such ~ that ~ p(x)=0 ~ and ~ grad ~ [f(x)- \lambda g(x)]=0\}[/math].
>what about specifically minima
No idea desu.

[Anonymous No.11272397]

>>11272313
fuck off nigger its an interesting question.
>jealousy at good working memory
brainlet detected

[Anonymous No.11272405]

>>11270075
Form a better question. What do you want to know? I guess the answer would be going through the course material an undergrad in chem or physics would go through.
>>11270928
This is the unique value [math] \phi=(\phi+1) / \phi [/math]. Rearrange and use the quadratic formula to find out that [math] \phi=(1+\sqrt{5})/2 [/math]. It is aesthetically pleasing, apparently. There are also other metallic ratios and the plastic ratio. Please don't watch "hurr durr golden ratio is everywhere isn't that magic" videos without realizing it is woo.
>>11269685
If nothing else, stop smoking weed. This is the one drug that eliminates dreams. Cigs and booze have little effect on me.
>>11269286
psilocybin
>>11271284
This is really easy to do in VBA. I don't know if libreoffice supports that.
>>11271868
>nobody knows how an airplane works
people often cite the Bernoulli principle, but this doesn't hold in conditions with flow separation. Wings work because viscous interactions between the surface of the wing and the fluid cause there to be a net downward flux of air through an imaginary surface surrounding the lifting body. lift does not exist in inviscid conditions. basically, people argue about this shit for hours. search "d'alambert paradox," "kutta condition," and "Kutta–Joukowski theorem".
>>11272313
If you have nothing to contribute, don't post, fag.

[Anonymous No.11272435]

>>11271284
Use the if function lmao.

[Anonymous No.11272451]

>>11271891
Idk. Zwitterion, with the 1- position deprotonated and the 9- position protonated?
What a dumb numbering scheme.

[Anonymous No.11272471]

>>11272300
Suppose your constraint gives rise to an embedding [math]g:M\hookrightarrow N[/math], then in general we can lift ([math]n[/math]-dimensional) Morse functions [math]f:N\rightarrow \mathbb{R}^n[/math] to a Morse function [math]h =g^* f:M\rightarrow \mathbb{R}^n[/math]. Since [math]g[/math] is a submersion, [math]dg[/math] is an injection of the tangent bundles [math]TM \hookrightarrow TN[/math] whence the critical loci satisfy [math]\operatorname{ker}dh \subset \operatorname{ker}df[/math], so we aren't "missing" any critical points on [math]M[/math] via the constraint [math]g[/math].
Now the stability at these critical loci are locally determined by the signs of the eigenvalues of the Hessian [math]H_h(x) = (d \otimes d) h (x)\in \mathbb{R}^{n\times n}[/math]; in particular, the index [math]\operatorname{ind}H_h(x) = \sum_{\lambda\in \operatorname{Spec}H_h(x)}\operatorname{sgn}\lambda[/math] is a topological invariant of Floer-type. Local minima are therefore characterized by the divisor [math]D_- \subset\operatorname{ker}dh[/math] containing points [math]x[/math] for which [math]\operatorname{ind}H_h(x) < 0[/math].
>>11272395
[math]\operatorname{grad}f[/math] is locally tangent to [math]M = \operatorname{im}g[/math], not normal.

[Anonymous No.11272478]

>>11272405
So... it's true? Nobody knows how an airplane works? What the fuck? We know quantum mechanics and general relativity.

[Anonymous No.11272481]

>>11272478
fluid mechanics is really, really complicated. quantum mechanics is nice and linear while fluid mech is absolutely disgusting. Saying "we don't know how an airplane works" is misleading, though. we know a whole fucking lot.

[Anonymous No.11272485]

>>11272478
the theory that explains how air moves over an airfoil has nothing to do with QM and GR, btw

[Anonymous No.11272489]

>>11272481
Well we know a whole fucking lot but we able to explain COMPLETELY, EXACTLY HOW an airplane flies?

[Anonymous No.11272493]

Time dilation, when one object accelerates, it experiences less time during travel than another object at rest. How does this work when motion is relative? For example, if two objects simultaneously and equally accelerate away from each other, which one experiences more time and which one experiences less time? It doesn't make any sense to me.

[Anonymous No.11272500]

>>11272489
i don't think we can COMPLETELY, EXACTLY explain anything
>>11272493
>if two objects simultaneously and equally accelerate away from each other, which one experiences more time and which one experiences less time?
they experience the same dilation wrt an inertial frame

[Anonymous No.11272646]

>>11272500
Let's say I have a fixed post sticking out of the ground with clock A at the top of the post. Extending from the post is an arm (of non-negligible length) perpendicular to the post. At the end of the arm, and sticking upward in the direction of the post (perpendicular to the arm) is clock B. So as the post rotates, clock B moves much faster than clock A (clock A is at rest excluding its local rotation, while clock B is doing circles around clock A). Now assume there is another arm extending from the position of clock B, also perpendicular to the post, and parallel to the first arm, extending back towards clock A from clock B. At the end of this arm is clock C. If I cause rotation of the post and these arms to cause clock C to maintain its position directly over top of clock A, will clock C age faster than A or the same speed? Because with respect to clock A, clock B is moving fast enough to experience less time during travel, and with respect to clock B, clock C is moving fast enough to experience less time during travel than clock B, and it just so happens that their movement causes clocks A and C to be stationary relative to each other. Does it depend on if the clock C arm rotation is accelerated by the clock B arm, or if it is actually fixed to the post and accelerated by the post directly?

[Anonymous No.11272743]

>>11272646
can you draw a diagram of what you mean? this isn't making sense to me

[Anonymous No.11272788]

>>11272743
motor underneath clock A forces clock B to rotate around clock A at some relativistic speed. """"""Separately"""""" a motor underneath clock B causes clock C to rotate the opposite direction around clock B at the same speed that clock B rotates around clock A, causing clock C to always be directly above clock A

[Anonymous No.11272934]

>>11272788
A and C read the same proper [math] t [/math] from the inertial perspective and B reads [math] \tau=t / \gamma [/math] from the same frame. see https://arxiv.org/pdf/gr-qc/0703090.pdf

[Anonymous No.11272989]

>>11272934
but relative to B, C should be travelling faster and experiencing less time than B... Imagine C was moving exactly as B was moving, not rotating around B, just moving with respect to A. After some time of this, both C and B have experienced less time than A. At one of the points in this rotation where C becomes directly above A again, C then starts rotating around B, as described in previous posts. C should now be experiencing even less time than B. For C to now experience the same time as A, that's like saying A is now being accelerated to the (angular) velocity of C.

Hopefully you understand my confusion

[Anonymous No.11273004]

I've taken two semesters of physics, calc I, and calc II and I still have no damn clue what a line integral is

if I'm understanding these videos right, is the line integral the area beneath the curve generated by the projection of a 3d curve onto a 2d plane?
Or, in other words, the area of the "shadow" of the curve?

[Anonymous No.11273027]

>>11273004
You have a vector (or scalar) field F in R^n. You have a path that moves through R^n. The line integral along that path is the summation of all the tiny little increments of "work" done by that field on an imaginary particle at each instant along that path.

[Anonymous No.11273056]

>>11273027
Different brainlet here, I'm confused. I mean yeah for a line integral through a vector field what you're saying makes sense, but for that pic >>11273004
isn't a line integral basically straight up just the area directly under the curve (not the projection)? Like it's the infinite summation of all those rectangles in the pic.

[Anonymous No.11273060]

I'm taking calc II despite not having touched math in 7 years. From what I see in my course outline, it's a continuation of antiderivatives and then a bunch of stuff I'll be learning for the first time.
Any tips as to what I should review from calc I? Any good sites for calc 2? Sticky led me to broken links.

[Anonymous No.11273073]

>>11273056
>isn't a line integral basically straight up
my guy I have no fucking clue, I'm just re-reading my electricity/electromagnetism textbook and trying to make intuitive sense of the formulas and at this point and I just don't know how since I have no idea how to picture a line integral

[Anonymous No.11273092]

>>11273073
Like you're the first one? I was mostly asking the second guy because he seemed to know.
I thought some simple line integral would just be the orange area.
The pic has the integral in respect to dx, so in that case I think it makes sense why it would be the projection.

[Anonymous No.11273116]

>>11273092
Yeah I'm the first guy who posted the picture.
Going off of your idea that the projection in the original is from integrating with respect to x, I assume the line integral with respect to y would be pic related

then integrating with respect to z would be the actual orange line rectangle segments of the original curve

[Anonymous No.11273448]

>>11273073
>>11273092
>>11273116
>>11273056
>>11273004
You have a path [math] \mathbf{r}(t):[a,b]\to\mathbb{R}^n [/math]. You have a vector field [math] \mathbf{F}:\mathbb{R}^n\to\mathbb{R}^n [/math]. The line integral of [math] \mathbf{F} [/math] along that path is given by
[eqn] \int_{\text{path}}\mathbf{F}\cdot\text{d}\mathbf{r}\equiv\int_a^b\mathbf{F}\cdot\dot{\mathbf{r}}\ \text{ d}t=\int_a^bF\dot{r}\cos\theta\text{ d}t [/eqn]
So, the line integral of a vector field along a path is the area under the magnitude of the field times the magnitude of the velocity of a particle along the path times the cosine of the angle between the field and the velocity, with respect to the parameter t, between times t=a and t=b. With a scalar line integral, it is the same shit.

[Anonymous No.11273460]

>>11273116
I think you're correct for y but no no not z, you need to find some variable that relate x & y. x & y can't be independent otherwise I don't see how you'd end up with a curve, you should end up with a surface. Then you'd integrate with respect to that variable, call it t. Although you need the length of the base ds of the small rectangles for the integral which is dependent on dt, and then you can use Pythagorean's theorem. So (z * ds) is the area of the infinitesimal line segment, and youll need to integrate that. (ds/dt)^2= (dx/dt)^2+(dy/dt)^2, or ds=root[(dx/dt)^2+(dy/dt)^2]dt. z is just the output of the function obviously. substitute both and you get the integral of f[x(t),y(t)]*root[(dx/dt)^2+(dy/dt)^2]dt, with bounds a&b for t.
I think this is right. I'm confused too tbqh, just some end gay near, but if nothing else this will bump the thread.

[Anonymous No.11273462]

>>11273448
Yeah I was just saying his pic just seemed to be depicting a scalar line integral.

[Anonymous No.11273470]

>>11273462
so you don't understand scalar line integrals? why?

[Anonymous No.11273481]

>>11273470
Well, I just wanted to make sure that the product of that integral was in fact the orange area. Although in his image it does use dx so in that specific case it seems to makes sense the output would be the projection, not sure though.

[Anonymous No.11273497]

>>11273481
>Well, I just wanted to make sure that the product of that integral was in fact the orange area
yes, it is

[Anonymous No.11273505]

>>11273497
oh, alright ok. but normally the integral is done with ds, in his image they use dx, in that case would it in fact be the projection?. You're basically taking the infinite sum of all the x components * the value of f(x,y) for all the rectangles. Is that correct?

[Anonymous No.11273509]

>>11273505
Yes, that is correct.

[Anonymous No.11273511]

>>11273509
Alright, thanks for your time.

[Anonymous No.11273515]

>>11273511
yw~ go to sleep now

[Anonymous No.11274017]

I'm looking for this textbook
Mark M. Benjamin, 2015, Water chemistry, Waveland Press, second edition, ISBN 1-4786-2308-X

I couldn't find it on libgen, is there somewhere else I can search or am i screwed and i actually have to purchase the thing?

[Anonymous No.11274032]

>>11273060
>what should I review from calc 1
Integration and differentiation.
You *probably* won't use the results about continuity.
>>11274017
We've all been spoiled by libgen, but sometimes you really just have to google it and work your way through the bullshit.
https://kupdf.net/download/water-chemistry-mark-benjamin-2nd-ed_58f731dedc0d60055cda9817_pdf

That's the website I got it from.

https://www.virustotal.com/gui/file/352aa6a1888fefc4e950133f6802bca17c23877bb2dcf5fa85560b585a1a1a1c/detection

That's the virus total.
Yes, I checked the pdf, it should be the correct book.

[Anonymous No.11274055]

>>11274032
>https://kupdf.net/download/water-chemistry-mark-benjamin-2nd-ed_58f731dedc0d60055cda9817_pdf
you're a saint, thank you so much anon

[Anonymous No.11274058]

>>11273060
http://tutorial.math.lamar.edu/Classes/CalcII/CalcII.aspx

look around the website for any material that you need a refresher on, he's covered calc1 and other classes too

[Anonymous No.11274306]

>>11268274
The Cobb-Douglas production function in economics; the center of growth theory.
How does this makes sense? How could you design a single production function for the whole economy, when there are so many different production proccesses going on, subject to increasing returns to scale, etc.?

Furthermore, what sense do diminishing marginal returns have when capital is not homogenous? If you have 4 workers and 4 calculators doing x work and you add one extra computer instead of an extra calculator, (supposing, obviously, that the computer is somehow superior to this calculator) the marginal productivity might as well be higher.

Did they designed the Cobb-Douglas just so it could fit with diminishing marginal returns and constant returns to scale?
Is this supposed to be science?

[Anonymous No.11274334]

>>11274306
>How could you design a single production function for the whole economy, when there are so many different production proccesses going on, subject to increasing returns to scale, etc.?
You couldn't, it's naturally going to be a very bad approximation.
>Furthermore, what sense do diminishing marginal returns have when capital is not homogenous? If you have 4 workers and 4 calculators doing x work and you add one extra computer instead of an extra calculator, (supposing, obviously, that the computer is somehow superior to this calculator) the marginal productivity might as well be higher.
Diminishing returns are for homogenous capital, that is, more calculators.
You can also think of it in terms of "decreasing returns on money invested into capital", where simpl heuristic arguments based on maximizing profits give decent reason for diminishing returns.
>Did they designed the Cobb-Douglas just so it could fit with diminishing marginal returns and constant returns to scale?
Yes.
>Is this supposed to be science?
Yes.
I think the issue you're having is that you're assuming that economists believe every economy's production can be described by a Cobb-Douglas.
This isn't the case. Economists aren't retarded.
Whenever an economist is tackling a problem, he's using the available data to approximate the problem. What you're looking at is a particularly simple approximation, and there's substantially more elaborate stuff out there.

[Anonymous No.11274355]

>>11274334
Thank you for your answer anon.
>Diminishing returns are for homogenous capital, that is, more calculators.
I understand this. But in reality, capital is not homogenous. Far from it, it's constantly changing. This abstraction would be a minor issue if it didn't affected the "diminishing marginal returns" thesis, as you seem to accept. If capital goods are heterogeneous and one is qualitatively better than anoter, diminishing returns might not be a thing, like in the example I provided. You can only accept them if you suppose capital goods are homogenous as the theory does. The diminishing marginal returns of the Cobb-Douglas seems good to capture the situation of a factory in a given moment, when obviously adding more machines with the same amount of workers has diminishing returns. But not so much to describe growth and a dynamic situation.
>Yes.
My problem with this is that it seems rather arbitrary. One should observe reality and then try to conceptualize it in abstract or analytic terms, and not the other way around. Even going as far as of 1776, Smith talked about increasing returns to scale as an argument for the expansion of commerce.
>This isn't the case. Economists aren't retarded.
But they still use it in almost every growth model.

[Anonymous No.11274384]

>>11274355
>I understand this. But in reality, capital is not homogenous. Far from it, it's constantly changing. This abstraction would be a minor issue if it didn't affected the "diminishing marginal returns" thesis, as you seem to accept. If capital goods are heterogeneous and one is qualitatively better than anoter, diminishing returns might not be a thing, like in the example I provided. You can only accept them if you suppose capital goods are homogenous as the theory does. The diminishing marginal returns of the Cobb-Douglas seems good to capture the situation of a factory in a given moment, when obviously adding more machines with the same amount of workers has diminishing returns. But not so much to describe growth and a dynamic situation.
No, even if we consider capital as not being homogenous, the situation still stands.
Instead of thinking about capital in terms of "amounts", think of them in terms of costs.
So for a given production, it's only natural that he'll first buy the capital which will bring him most profit, and gradually descend the ladder of capital quality.
>But not so much to describe growth and a dynamic situation.
Yes, we're fixing technological development.
>Even going as far as of 1776, Smith talked about increasing returns to scale as an argument for the expansion of commerce.
There's actually a historical argument about this.
You see, if most factories had increasing returns to scale, most fields would form natural monopolies. Economists of the time analysed the concrete situation of the time, and concluded that this wasn't the case.

Hardly applies today, naturally.
>But they still use it in almost every growth model.
If you have a better, more cost efficient approximation, feel free to write a paper about it and publish.
Just do remember that it needs to be based on data we can concretely accumulate.

[Anonymous No.11274517]

>>11274032
>>11274058
Thank you anons. Hoping for the best. Still trying to figure out the difference between antiderivatives and integrals, but I guess I'll figure it out this semester.

[Anonymous No.11274523]

would you rather have a chinese or indian professor teaching you math? assume accent

[Anonymous No.11274767]

How is [math] \mathbb{Z}/p [/math] defined? I only know it's a kind of field.

[Anonymous No.11274853]

How can I show a function is integrable on a given interval? is showing that it's continuous enough?

[Anonymous No.11274893]

>>11274523
Chinese.
>>11274767
Integers modulo p.
Usually simplified to [math]Z/pZ[/math], i.e. the quotient ring of Z modulo the ideal generated by p.
Also, p needs to be prime, otherwise it isn't a field.
>>11274853
If the interval is closed, yes. Closed specifically meaning it's in the form [a, b].
If it isn't, you'll need specific trickery.

[Anonymous No.11274936]

I'm a little bit confused. Where do I begin solving this? I never understood shit like this.
There is no friction, and 2m doesn't move in relation ship to 3m and m.

[Anonymous No.11274986]

>>11274767
>>11274893
OK, which is best notation?
[eqn]
\mathbb{Z}/p \\
\mathbb{Z}_p \\
\mathbb{Z}/p\mathbb{Z} \\
Z_p
[/eqn]
Personally I like the second one, since I'm too retarded for the [math]p[/math]-adic integers.

[Anonymous No.11274994]

>>11274517
I think what helped me differentiate (no pun intended) between them is to go back to definitions. The antiderivative [math]F[/math] of a function [math]f[/math] is a function that satisfies [math]F'=f[/math], while the integral [math]\int_a^bf[/math] is a real number, intuitively the area under the curve. You can compute an integral using an antiderivative by the Fundamental Theorem of Calculus.

[Anonymous No.11274997]

>>11274936
>Where do I begin solving this?
wtf is even the question?

[Anonymous No.11275009]

>>11274986
[math]\mathbb{F}_p[/math] is best.
Also, [math]\mathbb{Z}/p \mathbb{Z}[/math] isn't notation, it's the full definition.
[math]\mathbb{Z}[/math] modulo the ideal [math]p \mathbb{Z}[/math].

[Anonymous No.11275023]

>>11274997
Yes. Find F, if m=20 kg..
That fucking rolling block confuses me, because I don't understand which forces are applied to 2m.
I know which forces are applied to m (vertical mg=-T) (horizontal 1/6 F)
But which forces are applied to 2m? Sum of forces should be 1/3 F, right?

[Anonymous No.11275032]

>>11274936
>where do I even begin
The only force exerted on 2m is done by m.
Since there is no friction, the only force m does on 2m is gravity.
But 2m has the same acceleration and speed as 3m.

[Anonymous No.11275045]

>>11275032
So,
F2 = mg = 2m*a = (2m*F)/6m=1/3 F ?
mg=1/3F F=600N?

[Anonymous No.11275050]

>>11275023
Find F? I don't understand.
Nothing is even exerting a force on the 3m block.

Where did you get this retarded question from?
Can you just post the entire question?

[Anonymous No.11275060]

>>11275045
>1/3
No, the only force done on 2m is gravity.
Picture the situation if the large block was still.
m falls to the ground, and 2m is thrown off with accumulated speed.
We have a=g/2.
So F=4mg/2=2mg.

[Anonymous No.11275076]

>>11275050
>Nothing is even exerting a force on the 3m block.
It is pushing block. And this makes 2m not move relative to 3m
>Can you just post the entire question?
Yes.
a) Make a model.
b) Find F if m=20 kg
c) Now consider friction between 3m and 2m, and F is half of F in task b. Now what? Show all fucking forces excreted on 2m.
>>11275060
>Picture the situation if the large block was still.
You can't make accelerating things still. This is not inertial frame of reference.

[Anonymous No.11275080]

>>11275076
>You can't make accelerating things still. This is not inertial frame of reference.
Ah, I see why you're struggling, you're willfully going out of your way to misread things.

[Anonymous No.11275092]

>>11275080
Reading is hard, you know...
> F=4mg/2=2mg.
Why only 4m?

[Anonymous No.11275102]

>>11275092
Because it isn't exerting a force on 2m, only on 3m and m.
>shouldn't it also have to exert a force on 2m or something
It literally can't, because there's no attrition, so naturally it doesn't.

[Anonymous No.11275541]

>>11275102
While taking a bath I thought back on this for a second.
Essentially, I was considering the force done here (red circle) to be attrition and voiding it. I was thinking "magical rope which voids Newton's third law by teleporting forces from its ends since it doesn't have attrition or mass or whatever the fuck", but that might be completerly wrong.
If it doesn't count, tho, then it's F=3mg.

[Anonymous No.11275678]

>>11272451
Sounds somewhat reasonable as it should be at least a bit stable with 1-position deprotonated and 9-position protonated because of the carbonylgroups...
I feel like IUPAC makes things more complicated than it should...

[Anonymous No.11275877]

Suppose I have an arbitrary curve on a plane, maybe a circle or a square.
Is there any way to project the plane onto a line in such way that any vector inside the circle will be inside a particular line segment on the projected line? I think it isn't possible but I'm not sure.
Assuming it isn't, how about projecting the 2d curve onto a 3d line? Can we make it in such a way any vector inside the circle will be inside the line segment?

[Anonymous No.11275917]

>>11268274
Why is it that when you have a formula like [math]V={pi}r^{2}h[/math] and you're trying to find [math]\frac{dh}{dt}[/math], and you have both [math]r[/math] and [math]\frac{dV}{dt}[/math], you can't just plug in [math]r[/math] before you take the derivative, then take the derivative, plug in [math]\frac{dV}{dt}[/math] and solve for [math]\frac{dh}{dt}[/math]?

[Anonymous No.11275955]

>>11275917
*why can't you just plug in r

[Anonymous No.11276001]

>>11275917
think: if you are trying to find the slope of f(x) at a particular value of x, say x0, can you plug in x0 and then differentiate? no.

[Anonymous No.11276016]

>>11276001
oh okay that makes sense, thanks

[Anonymous No.11276225]

Nigger here, I have a thiery that says that -i stole it actually- smart people feel more bored than stupid people like me who feels exited and rushed and happy all the time
is it true?
and how does it feels to be so misarable lomao

[Anonymous No.11276283]

>>11275877
it's not possible. for example if you take a circle centered at the origin with diameter d, then any affine projection onto a line (not necessarily orthogonal) will map the circle to a line segment of length d. however if the line doesn't pass through the origin, you can map the circle onto any desired line segment with length d.

[Anonymous No.11276350]

why, here, is 6*dirac = (t-2)(-3*dirac) ?

[Anonymous No.11276476]

>>11276350
[math](t-2)(-3 \delta)=6 \delta -3t \delta[/math].
In other words, [math]-3t \delta = 0[/math].
You can check this from the definition of multiplication of a distribution by a function.
>>11276225
>is it true
No, not really.

[Anonymous No.11276480]

>>11276476
I mean, how would you derive (t-2)(-3*dirac) from 6*dirac. Feels like I'm missing something obvious here.
appreciate it!

[Anonymous No.11276510]

>>11276480
I guess it has something to do with <dirac,phi> = phi(0) so -3*t*dirac always is -3*0*dirac?

[Anonymous No.11276518]

>>11276480
>how would you derive (t-2)(-3*dirac) from 6*dirac.
You mean not why it works, but how you'd come up with it?
Intuition, I guess.

[Anonymous No.11276521]

>>11276518
>Intuition
ah yes, the best proof
anon p-pls ;_;

[Anonymous No.11276524]

>>11276521
The proof outline is already here >>11276476
Could you be more specific about what you want explained?

[Anonymous No.11276531]

>>11276524
A reasoning as to why (t-2)(-3*dirac) is chosen to be derived from 6*dirac, and not (1891329898312*t - 2)(-3*dirac) because clearly that's correct too.

but I think I figured it out. you want to compare (t^2-2t) on the LHS to something on the right hand side with 6*dirac, so you just put something close to (t^2-2t) on the right side and work your way from there

[Anonymous No.11276536]

>>11276531
>you want to compare (t^2-2t) on the LHS to something on the right hand side with 6*dirac, so you just put something close to (t^2-2t) on the right side and work your way from there
Yes, exactly.

[Anonymous No.11276545]

>>11276531
1*0 + 1 = 2
>I don't get it! Why can't you say
>1891329898312*0 + 1 = 1?

[Anonymous No.11276676]

>>11276283
>however if the line doesn't pass through the origin
You mean if the circle isn't centered at the origin? Can you give an example of transformation mapping a circle into a line segment? I'm a brainlet regarding linear algebra.

[Anonymous No.11276680]

How can I show that this thing goes to infinity as x approaches infinity?

[Anonymous No.11276684]

>>11276680
Show that for any [math] I(x) [/math] we have [math] x'>x \implies I(x')>I(x) [/math]

[Anonymous No.11276685]

can you guys help me understand how to get to the expression in red? possibly with explicit steps because i'm retarded

[Anonymous No.11276693]

Noob here. If I wanted to get a neural network to play Minecraft, where would I start?

[Anonymous No.11276698]

>>11276676
[math](x_1, x_2) \rightarrow (x_1, 0)[/math].
>>11276680
[math]\frac{t-1}{\log t}[/math] is literally nondecreasing and constantly positive when t>1.
>>11276693
>get a seed for a nice map
>go to tensorflow

[Anonymous No.11276702]

>>11276676
>You mean if the circle isn't centered at the origin?
no

[Anonymous No.11276717]

>>11276698
Can't I just compare it with another integral that goes to infinity but is not greater than the original? Like x^(1/2)

[Anonymous No.11276737]

>>11276717
You don't need to.
Just compute the derivative, show it's positive, and then bound the function below by a constant.

[Anonymous No.11276755]

>>11276737
The conditions would be that the function is increasing and positive for t greater than some n? And then I can conclude that the function goes to infinity?

[Anonymous No.11276800]

>>11276702
Your statement was a bit confusing.

[Anonymous No.11277114]

>>11268980
Eigenvalues and eigenvectors are just another way of describing a matrix in its "natural" basis. For now, we'll restrict to normal matrices [math]A \in \mathbb{C}^n[/math], i.e. satisfying [math] [A, A^*] = 0 [/math], as these are guaranteed to have a spectral decomposition. [math]A^*[/math] is the adjoint (conjugate transpose) of [math]A[/math], [math][\cdot, \cdot][/math] is the commutator. (Non-normal matrices may or may not have eigenvalues). This means there is a (multi)set of eigenvalues [eqn]\sigma(A) = \{ \lambda_k \in \mathbb{C} \}_{k=1}^n[/eqn] called the spectrum of [math]A[/math], and a corresponding (orthonormal) eigenbasis [eqn]\mathcal{B}(A) = \{ v_k \in \mathbb{C}^n \}_{k=1}^n ,[/eqn] satisfying the usual eigenvalue equations [eqn]Av_k = \lambda_k v_k .[/eqn] The spectral decomposition of [math]A[/math] is then [eqn]A = \sum_{k=1}^n \lambda_k v_k v_k^*.[/eqn]

In other words, the eigenvectors of [math]A[/math] defines the basis in which the matrix is diagonal, and the eigenvalues are the those diagonal values in that basis. This is useful for various reasons, primarily because a matrix in diagonal form is very easy to work with. For example, if you want to calculate [math]f(A)[/math], where [math]f : \mathbb{C} \to \mathbb{C}[/math] and we extend its definition to linear operators by the Borel functional calculus, then we simply have to evaluate [math]f(\lambda_k)[/math], i.e. [eqn]f(A) = \sum_{k=1}^n f(\lambda_k) v_k v_k^*[/eqn]. In the case of matrices, this is equivalent to computing the Taylor series of [math]f[/math] using matrix-valued arguments, but the spectral form is much more convenient to work with. (In the case of infinite dimensional vector spaces, the Taylor series approach doesn't even work at all if your operator is unbounded.)

[Anonymous No.11277208]

What is [math] \oplus [/math] in [eqn] U \oplus V=\mathbb{R^{3}} [/eqn] if U and V are linear spaces?

[Anonymous No.11277239]

>>11277208
https://en.wikipedia.org/wiki/Direct_sum

Just think of the elements of U and V stacked on top of each other.
E.g. if a in U and (b,c) in V and U, V are vector spaces, then
(a,b,c) is in U+V.

This + for vector spaces is different than for sets, where it denotes the disjoint union.
E.g.
E.g. if a in U and (b,c) in V and U, V are sets, then
{0, a} and {1, (b,c)} would be elements of U+V.

Generally, those constructions have one universal property as expressed in category theory by
https://en.wikipedia.org/wiki/Coproduct

[Anonymous No.11277342]

>>11277208
Is there ever a distinction between [math]V\times W[/math] and [math]V\oplus W[/math] if [math]V[/math] and [math]W[/math] are vector spaces?

[Anonymous No.11277355]

>>11277342
IIRC [math]V \times W[/math] is a set, while the other one is a vector space.

[Anonymous No.11277364]

>>11277355
OK I understand. Thanks desu

[Anonymous No.11278020]

Where can I find the solutions for Calculus and Analytic Geometry 9th edition by Thomas and Finney?
I searched libgen, found nothing so I googled for it but the only website that had it wanted credit card information. The other editions are very different from the 9th one so I can't really use those.


And also in general, where do you find solutions for books for free?

[Anonymous No.11278026]

how can I get rid of or reduce scars at home? about 3 years old now and mostly faded color wise

[Anonymous No.11278117]

>>11278020
>calc and analytic geometry
Just copy and paste the entire problems into Wolfram Alpha.

[Anonymous No.11278137]

I have seen reactions to reduce alkene to alkane which functionalize both sides in all sorts of combinations. Brominate one side and fluorinate the other, aminate both sides and so on and so on. What I haven't seen yet, or at least I haven't been able to find, is a way to break an alkene into alkane while adding an amine on one side and a double-bonded oxygen on the other. Altho I suppose a hydroxyl on one side and a double-bonded nitrogen would be good as well. Any takers?

>>11268799
The links to one of the hosts are all fucked up. Go to libgen.pw, almost all books have more than one host there.

[Anonymous No.11278167]

>>11268274
Suppose I have a multivariable function. For example, f(x, y) = x^2 + 3xy + y^2. I only care about values where x and y are natural numbers. Is there a way for me to make a new function of one variable, g(t), such that it yields all the values of f(x, y) in increasing order? So
g(1) = 5
g(2) = 11
g(3) = 19
g(4) = 20
g(5) = 29
g(6) = 31
g(7) = 41
g(8) = 44
g(9) = 45
etc.

Any help you can offer is greatly appreciated.

[Anonymous No.11278245]

if I get absolutely shitfaced, BAC of 1%, then have a complete blood transfusion would it sober me up completely?

[Anonymous No.11278316]

>>11278117
Honestly not a bad a idea.
Thanks anon.

[Anonymous No.11278317]

>>11278137
Most likely opening an epoxide/aziridine with their respective nucleophiles, followed by a Swern-type oxidation. Were you looking for one step?

[Anonymous No.11278322]

>>11269079
that's a devo hat

[Anonymous No.11278376]

>>11278317
One step or one pot, yeah. Otherwise, I already have it sketched out. I'm trying to optimize it.

Since I have your attention, another option for my issue would be a reaction which brominates a benzene ring and a cycloalkyl ring at the same time. Whether or not they have heteroatoms, would be fine either way.

>>11278167
I'm not the mathanon, but for whatever it's worth, you can probably parameterize it, assuming you know what kind of curve it describes so you can parameterize it correctly. Instead of one equation with 2 variables, you would have 3 equations (each one describing one of the 3 coordinates) with a single same variable, so you can't have a neat single g(t) equation with a single variable.

>>11271072
>Urysohn's lemma's proof's shape.
I actually expected some sort of ligma-like joke when I put that into Google.

[Anonymous No.11278386]

>>11278376
NBS can be used for electrophilic bromination, then subsequently you might expose it to light for a wohl-ziegler. Technically two steps, potentially one-pot.
For your earlier question, also try looking into N=N-O 1,3-dipole addition and whether the resulting heterocycle can be reduced

[Anonymous No.11278513]

>>11278386
Will look into it, thank you very much. Have some blueboard tits.

[Anonymous No.11278981]

How do I keep my brain active after my studies are complete?
I want to slow the decline as much as possible.

[Anonymous No.11279214]

>>11277239
I know that U has 3 dimensions, so it's neither of the two. I'm guessing V is supposed to be a vector space that generates [math] \mathbb{R^{3}} [/math] when merged with U

[Anonymous No.11279217]

>>11278026
reddit.com/r/SkinCareAddiction

[Anonymous No.11279309]

Why do hazard suits have a gas mask inside the suit itself? Doesn't the suit isolate from agents and substances in the environment? Why have a gas mask then?

[Anonymous No.11279351]

>>11278376
>I'm not the mathanon, but for whatever it's worth, you can probably parameterize it, assuming you know what kind of curve it describes so you can parameterize it correctly. Instead of one equation with 2 variables, you would have 3 equations (each one describing one of the 3 coordinates) with a single same variable, so you can't have a neat single g(t) equation with a single variable.
I seriously doubt there is some mechanical procedure that produces an equation which is reasonable to compute.
Consider, for example, Fermat's curve [math]f(x, y)=x^n+y^n[/math].
You automatically turn the problem into showing that [math]f(t)[/math] doesn't have n-th powers in its images for t natural, and otherwise reduce diophantine equations to one-dimensional problems.
It's such a convenient trick for number theory that I imagine I'd have heard about it.

Absolutely could be wrong, tho.
>>11279214
>U has three dimensions
There are exactly two options:
>V is trivial
>[math]U=R^3[/math], [math]V \subset R^3[/math], and the author was doing some serious abuse of notation while talking about the internal sum U+V

>it's neither of the two
The symbol isn't really used for anything else desu.
>>11279309
If it did isolate, people would still need to use oxygen masks.

[Anonymous No.11279352]

>>11277355
NO

>>11277342
no. there's a distinction only if we're talking infinite products/sums.

[Anonymous No.11279376]

>>11279214
Nevermind. It's direct sum.

[Anonymous No.11279436]

Can someone deliberate and expand upon this image on how exactly the fourier transform of sgn(t) is -2iw^-1 ?

[Anonymous No.11279444]

>>11279436
oh I think I get it....
sign function is basically the heaviside function times 2, minus 1?

these studies are fucking dumb

[Anonymous No.11279448]

>>11279444
>sign function is basically the heaviside function times 2, minus 1?
Yes.

[Anonymous No.11279456]

>>11279448
after thinking about shit like this for hours I usually figure it out after asking the question to someone

thanks

[Anonymous No.11279458]

>>11279456
Don't worry, everyone here does that.

[Anonymous No.11280172]

I don't know much math, but I need to figure out something about conformal mapping. Is there a linear fractional transformation which takes the region inside a disk of radius r centered at some point over the negative real axis to a region to the right of the line x = r? How can I find such transformation?
Pic related.

[Anonymous No.11280181]

>>11278981
You keep learning new techniques, talk with people in fields or industries adjacent to yours, and ideally read a lot of papers regardless if you're on the research side of things or not. Most people who receive a good STEM education and get hired into industries where they're using what they've learned need to continue some form of self learning to remain competitive, and often because they're curious about what they learned beyond the economic utility it might provide to them. If you're going into academia then you ought to be reading papers on a daily basis anyway and that will ultimately lead you to new information you haven't learned yet or which was not properly expounded when you were in school so you have nothing to worry about assuming you don't want to become a senile boomer faggot instructor that knows about half of the undergrad material.

[Anonymous No.11280189]

>>11279352
Original asker here, OK I see there is a difference for infinite products/sums. But if they're finite, then the product and direct sum are the same, right?

[Anonymous No.11280373]

>>11280172
There's a fractional linear transformation which sends the unit circle to the half plane. See i.e. here https://math.stackexchange.com/questions/114733/mapping-half-plane-to-unit-disk
You can the follow it up with a fractional linear transformation which rotates the complex plane 270 degrees, (i.e. multiplication by -i), sending the upper half plane to the right half plane, and then translate the thing right.
>>11280189
If they're finite, yes.

[Anonymous No.11280398]

>>11280373
Small mistake, that link is the map which sends the right plane to the unit ball.
I trust you can figure out the remainder of the problem's geometry on your own (translating the circle so its center is zero, inverting the map in the link, etc.)

[Anonymous No.11280485]

>>11280373
The transformation w=(1+z)/(1-z) maps the unit disk to the half plane, but it maps disks of radii other than one to other disks. How can I generalize this transformation so that it takes a disk of radius R to the half plane?

[Anonymous No.11280501]

>>11280485
[math]| \frac{z}{R} | = \frac{ | z |}{R}[/math]

[Anonymous No.11280513]

>>11280172
log(z)=log(|z|)+i.arg(z)

[Anonymous No.11280562]

>>11268274
Is there an explicit formula for the sequence of squares and cubes? n^2 and n^3 are pretty simple, but for some reason I can't come up with a formula that would yield 1,4,8,9,16,25,27,36, etc.

[Anonymous No.11280629]

>>11280562
the formula is literally n^2 and n^3, what else more do you want
you'd be just rewriting n^2 and n^3

[Anonymous No.11280706]

>>11280629
I want a formula that gives the squares and cubes in order. Such that:
f(1) = 1
f(2) = 4
f(3) = 8
f(4) = 9
etc.

I want just one formula, not to have to pick by inspection which one will generate the next number.

[Anonymous No.11280756]

>>11280501
Thanks, I figured it out. It was easier than I thought and I feel kinda retard now.

[Anonymous No.11280901]

>>11278167
you should realize what you are asking is very hard. For example consider the function f(x,y,z)=x^3+y^3-z^3. Then asking whether g(1)>0 is equivalent to Fermat's last theorem (for k=3).


In general, no algorithm to do what you propose can exist, since it would contradict Matiyasevich's negative solution to Hilbert's 10th problem

[Anonymous No.11280911]

>>11280901
Wow, sounds complicated. I guess I realized it was hard for me, but I didn't realize a solution did not exist. (or at least has not been discovered yet?) Thank you.

[Anonymous No.11280918]

>>11280901
To follow up, is there not even a general algorithm when there are two variables?

[Anonymous No.11280943]

>>11280901
>For example consider the function f(x,y,z)=x^3+y^3-z^3. Then asking whether g(1)>0 is equivalent to Fermat's last theorem (for k=3).
how?

[Anonymous No.11280969]

>>11280943
g(1)=0 iff there exist x,y,z such that f(x,y,z)=0

[Anonymous No.11280991]

>>11268274
Hey
How do I do exponentation if the powers are fractions or decimals

Should I treat 3 - 6^3 as 3 - 216 as in is it -6^3 or not? Because if 6^2 then it is 3 + 36?

[Anonymous No.11281014]

Explain step by step how to:

2/4 + 6/7

[Anonymous No.11281043]

>>11280991
3-6^3 = (3) + (-1)*(6^3)

>>11281014
2/4 + 6/7
0.5 + 6/7
0.5 + 0.857
1.357

[Anonymous No.11281047]

>>11281014
Multiply first term by 7/7 and second term by 4/4,

2/4*7/7 + 6/7*4/4

which is the same as

(2*7)/(4*7) + (6*4)/(7*4)

then carry out the multiplications

14/28 + 24/28 = (14+24)/28 = 38/28 = 19/14

[Anonymous No.11281218]

1. Does every group appear as the galois group of some galois extension?
2. Can anything nonobvious be said about two galois extensions with isomorphic groups?( Assuming the base field is the same in both)

[Anonymous No.11281265]

>>11281218
>Does every group appear as the galois group of some galois extension?
https://en.wikipedia.org/wiki/Inverse_Galois_problem

[Anonymous No.11281325]

question about the d'alembert operator, what is the difference between a downstairs differential and an upstairs differential? is it literally just the derivative acting on a contravariant or covariant vector? does it matter that the operator is defined as pic related instead of the other way around?

if it is just the derivative acting on a (co/contra)variant vector, what would happen if i did a covariant derivative on a contravariant vector, would it just be undefined? zero?

[Anonymous No.11281330]

Very stupid, but a question still.

8a^-4 / 4p^3 = 2a^-1 = - 2a

Is this correct?
Just need a reminder.

[Anonymous No.11281334]

>>11281330
no. why would that be true?

[Anonymous No.11281337]

>>11281334
Is it 2/p then? I don't remember how negative exponentation works. Is it 1/x^n for x^-n?

[Anonymous No.11281340]

>>11281337
2/a*

[Anonymous No.11281343]

>>11281337
Its 2a^-4/p^2 = 2/a^4p^2
What the fuck anon

[Anonymous No.11281344]

>>11281340
>>11281337
"no"

[Anonymous No.11281346]

>>11281344
>>11281343
I'm lost.
isn't it
a^m / a^n = a ^ m - n?

[Anonymous No.11281347]

>>11281346
Oh wait I'm retarded. Swap p for a, they're the same term.

[Anonymous No.11281349]

>>11281330
OK let me change this.

8a^-4 / 4a^3
2a^-1
2a^-1/1
2/a^1
Thus
2/a

[Anonymous No.11281350]

>>11281347
if p=a then the first expression in >>11281330 is equal to 2/a^7

[Anonymous No.11281351]

>>11281349
still no

[Anonymous No.11281352]

>>11281350
But anon, how can I add the terms if I'm dividing, not multiplying?

[Anonymous No.11281354]

>>11281352
i dont know what this means. I am 100% certain of my result, btw

[Anonymous No.11281355]

>>11281351
Why not? Why wouldn't I subtract the powers if I'm simplyfing? I thought you faggots knew math.

[Anonymous No.11281356]

>>11281350
Oh wait you're right.
I was having a retard moment. Good to know some of you guys are alright.

[Anonymous No.11281360]

>>11281355
Because [eqn] \frac{4a^{-4}}{2p^3}=\frac{2a^{-4}}{p^3}=2a^{-4-3}=2a^{-7}=\frac{2}{a^7} [/eqn]
oh my fucking god

[Anonymous No.11281363]

>>11281360
Where did you get p from, faggot?

[Anonymous No.11281364]

>>11281325
Pretty sure physicists just consider [math]\partial ^{\mu} \partial _{ \mu} = \partial _{\mu} \partial ^{\mu} [/math].

[Anonymous No.11281366]

>>11281363
is this a goddamned joke? enjoy your final (You)

[Anonymous No.11281377]

>>11281366
Life is struggle.

[Anonymous No.11281417]

I recently started sending messages to strangers in the middle of the night, to multiple people.

They contained a few typos which I would usually correct and didn't really made sense (context wise).
For example, at 5 in the morning, I shot a message to my mom telling her she shouldn't panic because I was sleeping at a friend's house that night, one minute later, I sent a message to my dad saying I was staying at a friend's house, so there should be "no interference". (Unsure whether I was saying he shouldn't interfere, can paste the exact messages if asked). Except at that time I was safe and sound in my bed, I went to sleep like one or two hours prior to sending the messages.
It's already happened that I'd wake up and say something then not remember it at all (for example roommate entering room, apologizing because he didnnt think I'd be sleeping so early and I'd tell him "no worries dude" but had absolutely no memories of having said that)
Is this the beginning of dementia bros?

Real question : Anybody knows any good papers on somnambulism and messaging?

I don't want this to continue and send someone an awkward message.

[Anonymous No.11281688]

>>11281363
[eqn]\frac{8a^{-4}}{4a^3} = \frac{2a^{-4}}{a^3} =2a^{-4-3} = 2a^{-7} = \frac{2}{a^7}[/eqn]

[Anonymous No.11281749]

If tomorrow I wake up on an island with no reference materials or tools, how and in what order should I calculate
>pi, e, sqrt 2
>log and trig tables
>common exponents
>local physical constants like gravity and pressure

[Anonymous No.11281753]

>>11281749
You cannot calculate pi, e and sqrt 2 unless you already know the gravity and pressure. So you are in a bind.

[Anonymous No.11281782]

>>11281417
>Is this the beginning of dementia bros?
Probably. Go see therapist.

[Anonymous No.11281799]

>>11281417
>It's already happened that I'd wake up and say something then not remember it at all (for example roommate entering room, apologizing because he didnnt think I'd be sleeping so early and I'd tell him "no worries dude" but had absolutely no memories of having said that)
That one is probably more common, happened to me a few times, when someone woke me up to ask me something and I'd respond with something and then go back to sleep immediately.

[Anonymous No.11281810]

[Anonymous No.11281830]

How can I start going about building a humanoid robot? I only need directions for the question,you can freely disregard everything after this fullstop. I will program it with consciousness and humanlike intelligence.

[Anonymous No.11281844]

how do i know if i have OCD? just read checklist online?

[Anonymous No.11281862]

>>11268301

I could be wrong but here is my guess:

Initiation of lipid peroxidation results from production of ClCO• and Cl• radicals when phosgene reacts with unsaturated lipids in the lungs, despite its somewhat hydrophobic nature. This creates horrific products like HCL and formaldehyde which oxidizes easily in the lungs to formic acid then finally decomposes to CO and H2O.

[Anonymous No.11281933]

>>11281844
depends (will you start pacing around the room after reading this post?

[Anonymous No.11282035]

>>11281933
lol, i think i might have OCD without C.

[Anonymous No.11282152]

For those of you on adderall or ritalin or w/e, how many mg are your doses?

[Anonymous No.11282256]

>>11268274
Why can I plug in [math]y[/math] before I take the derivative? I thought you couldn't plug in a number before you take the derivative. For instance, with [math]V=(\frac{1}{3})(\pi)(r^2)h[/math], where we're looking for [math]\frac{dh}{dt}[/math] and we're given both [math]r[/math] and [math]\frac{dV}{dt}[/math], you \mathbf{cannot} plug in [math]r[/math], take the derivative, plug in [math]\frac{dV}{dt}[/math], and find [math]\frac{dh}{dt}[/math]. But in the case of what's happening in my image, it seems that you \mathbf{can} plug in [math]y[/math] before you take the derivative, and then proceed to take the derivative and solve for [math]\frac{dx}{dt}[/math]. What's the difference here?

[Anonymous No.11282278]

Why can I plug in [math]y[/math] before I take the derivative? I thought you couldn't plug in a number before you take the derivative. For instance, with [math]V=\frac{1}{3}\pir^{2}h[/math], where we're looking for [math]\frac{dh}{dt}[/math] and we're given both [math]r[/math] and [math]\frac{dV}{dt}[/math] , you cannot plug in [math]r[/math] , take the derivative, plug in [math]\frac{dV}{dt}[/math] , and find [math]\frac{dh}{dt}[/math] . But in the case of what's happening in my image, it seems that you can plug in [math]y[/math] before you take the derivative, and then proceed to take the derivative and solve for [math]\frac{dx}{dt}[/math] . What's the difference here?

[Anonymous No.11282282]

>>11282278
[math]\frac{1}{3}\{pi}r^{2}h[/math]

[Anonymous No.11282320]

>>11282278
They didn't plug anything in before differentiating, they substituted and then differentiated implicitly

[Anonymous No.11282359]

>>11282320
Sorry I meant plug in 1 for y, aka substituting 1 for y

[Anonymous No.11282536]

>>11282278
>>11282359
I already answered you here >>11276001

>>11280629
>

[Anonymous No.11282553]

>>11282536
I'm asking why does it work for one and not the other. With one, I can't substitute r before I take the derivative. In the other I can substitute y before I take the derivative

[Anonymous No.11282602]

>>11282553
Because then you get dx/dt = 0 and that makes no sense. Never and nowhere can you plug in values of a function before differentiating to the the slope.

[Anonymous No.11282633]

>>11282602
except that that's what happens in my image
>>11282278

the standard form for tangent is [math]tan \theta = \frac{x}{y}[/math] , but they plugged in 1 for y and got [math]tan \theta = x[/math] . Then they took the derivative. So they plugged in the value for y before differentiating.

[Anonymous No.11282644]

>>11282633
Because the radius of the unit circle is unchanging. tangent θ is in no way a function of y, here. Nothing is being "plugged in"

[Anonymous No.11282650]

>>11280562
No idea. There probably isn't.
What I do know is this:
>there is no explicit formula as a polynomial, since it grows slower than x^2, but also isn't linear
>computing an inverse function is extremely easy, you just consider that the number of squares smaller than n is [math]\lfloor n^{1/2} \rfloor [/math] and using numerical methods to compute it's inverses might be efficient
>>11281749
>how
>pi
Archimedes's technique, so you approximate the circle by n-sided polygons and let n be large enough.
>e
Euler's series or the classical definition.
>sqrt 2
Newton.
>log
Integral of 1/t from 1 to x, trapezoid method.
>trig
Recall that [math]sin(x)=e^{ix}-e^{-ix}[/math], and similarly [math]cos(x)=e^{ix}+e^{-ix}[/math], use that and Euler's to expand the series and compute.
>common exponents
Use the log table.
>local physical constants
I genuinely can't come up with any method of making a chronometer in an island.
>in what order
Fuck if I know.
>>11281417
>I do stuff while asleep
>do I have dementia
As a layman, I diagnose you with somnambulism, and suggest further trials for hypocondria.
>>11281830
>>>/diy/sqt
>>11281844
Talk with a doctor.

[Anonymous No.11282669]

>>11282650
>Recall that sin θ = ... and cos θ = ...
You're missing respective leading constants of 1/2j and 1/2 on the RHS of each of those equalities, hun

[Anonymous No.11282673]

>>11282669
Oh yeah, thanks lad.

[Anonymous No.11282687]

>>11282673
Wait, wasn't there also an i in the sine?

[Anonymous No.11282692]

>>11282687
Right. There's a j. That's what I said.
[eqn] \sin\theta=\frac{e^{j\theta}-e^{-j\theta}}{2j} [/eqn]
[eqn] \cos\theta=\frac{e^{j\theta}+e^{-j\theta}}{2} [/eqn]

[Anonymous No.11282705]

>>11282692
Right, my bad.
Thanks for the refresher.

[Anonymous No.11282744]

how come a laser being directed away from your eyes can steel be seen by you?

[Anonymous No.11282745]

how come a laser being directed away from your eyes can still be seen by you?

[Anonymous No.11282764]

>>11282744
>>11282745
the laser is reflecting off of tiny bits of dust and shit suspended in the air.

[Anonymous No.11282769]

>>11282764
how come you can see lasers in space when you are in space?

[Anonymous No.11282773]

>>11282644
>Nothing is being "plugged in"
call it whatever you want. 1 is being replaced with y because [math]y=1[/math] . With [math]V=\frac{1}{3} \pi r^{2}h[/math] ,if I'm given [math]r=5[/math] , I cannot replace 5 with r before I differentiate like I could with y.

[Anonymous No.11282774]

>>11282769
You can't.

[Anonymous No.11282775]

>>11282769
I don't believe you can.

[Anonymous No.11282782]

>>11282773
>y=1=radius of circle
And yet y is not a variable in the pic you posted. The radius of the circle that composes the x-section a cone IS a variable.

[Anonymous No.11282812]

>>11282782
So both y and r represent radii of a circle, but r is a variable and y is not?

[Anonymous No.11282823]

>>11282812
Look, dude. It depends on the fucking context. Does the function depend on a term that varies? Then you are not allowed to treat that term like constant and not allowed to "plug in" before differentiation. I don't know how to explain this in any simpler way.

[Anonymous No.11282847]

>>11282823
But if r=5, it doesn't vary, because you know, it's 5. 5 is a constant.

[Anonymous No.11282854]

>>11282847
The context is very important. I don't know what the context is.

[Anonymous No.11282867]

>>11282278
>What's the difference here?
He isn't doing what you think he's doing. The argument for [math]x = \tan \theta[/math] is clean and geometric, it doesn't come from analytic geometry or calculus, and he's doing no manipulation of either of those.

[Anonymous No.11282872]

>>11282854
Here's your context. They got [math]r= \frac{2}{5} h[/math] from the figure, and then I plugged in [math]h=6[/math] to find r and got [math]r= \frac{12}{5}[/math] . Then I substituted that value for r before differentiating and it wouldn't work.

[Anonymous No.11282882]

>>11282872
Just glancing at the pic I can see that r varies. It is not a constant.

[Anonymous No.11282909]

>>11282882
Isn't the point of a variable to be a placeholder for unknown information? r is a known quantity at h=6

[Anonymous No.11282912]

>>11282872
The issue is precisely that r is a function of h.
So when you're computing the change of V in function of h, you're disregarding the change that goes [math]\delta h \rightarrow \delta r \rightarrow \delta V[/math], and the calculation comes out wrong.
You need to make sure *all* the effects of the infinitesimal change in r show up in V.

[Anonymous No.11282925]

>>11282912
i'll take your word for it. maybe when i get into higher mathematics i'll understand the theory behind it better

[Anonymous No.11282940]

>>11282925
I'll try to explain it more explicitly.
We have [math]V(h, r)[/math], the volume is a function of the radius and the height. Since [math]r(h)[/math], we can also give the volume as exclusively a function of the height,, [math]V(h(r), r)=V(r)[/math].
So if we let r change by [math]\delta r[/math], then we can compute either [math]V(r+ \delta r)[/math] or [math]V(h, r + \delta r)[/math].
These are two different things, and knowing when to use which depends on context, so you'll figure it out with practice.

[Anonymous No.11282946]

>>11282940
>Since [math]h(r)[/math]

I have no idea why I'm mixing these two up so much.

[Anonymous No.11282948]

>>11282909
>r is a known quantity at h=6
And yet it still varies throughout the cone. Hence r is a VARIable. In the case of one circle, r does not vary and is not a VARIable.

[Anonymous No.11282959]

>>11282650
no explicit polynomial
Yeah that makes sense. I wonder if there is a way to do it with trigonometry? I can make a function which alternates between x^2 and x^3 values, so it yields all the perfect squares and cubes, but it is unsorted. I have no idea how you would make a function that spits them out sorted.

I'm not sure what you mean by your second point about inverses though.

[Anonymous No.11282990]

what is, scientifically, the best daily routine?

or is it best to just not ask such questions, and go day by day, optimizing each day individually, moment by moment? Probably the latter

thank you and goodnight

[Anonymous No.11283013]

>>11282940
this is a better explanation, thanks

[Anonymous No.11283279]

>>11282959
>I'm not sure what you mean by your second point about inverses though.
The number of n-th powers smaller than i is [math]floor(i^{1/n})[/math].
So the inverse of the function you want is [math]floor(n^{1/2})+floor(n^{1/3})-floor(n^{1/6})[/math] , and the six is there to remove doubles.
You can try to numerically invert this. It might or might not be more efficient than just calculating it the old way.

[Anonymous No.11283324]

>>11283279
That's actually really interesting, and sounds quite fruitful, thank you.

[Anonymous No.11283428]

>>11281325
They transform differently, one as [math]\partial \mapsto g\partial[/math] and the other as [math]\partial \mapsto g^{-1}\partial[/math]; however,as bases of [math]T^{1,0}M[/math] and [math]T^{0,1}M[/math] which are naturally dual, that is the extent of their difference on flat spacetimes. However, on curved sapcetimes the Laplace-Beltrami operator [math]\Delta f= \operatorname{tr}H_f[/math] reads in coordinates [math]\partial_i (g^{ij}\partial_j f)[/math], where [math]H[/math] is the Hessian [math]H_f = (d^*\otimes d)f \in \operatorname{End}V[/math], and we use the metric tensor [math]g[/math] to identity [math]\operatorname{End}V \cong V^*\otimes V[/math]. Hence the order of the differentials matters unless [math]g[/math] is symmetric.

[Anonymous No.11283471]

>>11281325
the operators commute and the metric is constant so it doesn't matter. the operators are the same:

[math]\partial_{\mu}\partial^{\mu} = \partial_{\mu}(\eta^{\mu\nu}\partial_{\nu}) = \eta^{\mu\nu}\partial_{\mu}\partial_{\nu} + \partial_{\mu}(\eta^{\mu\nu})\partial_{\nu} = \eta^{\mu\nu}\partial_{\mu}\partial_{\nu} + 0 =\partial^{\mu}\partial_{\mu} [/math]

>>11283428
lol, yukari with the worthless explanations as usual. Always flexing with his faggot math shit. Literally homosexual tier: Dispensable Erudition.

[Anonymous No.11283819]

>>11283428
Wait, isn't [math]g[/math] always symmetric?

[Anonymous No.11283826]

>>11283471
no u
>>11283819
In standard GR yes, but you can do away with the assumption.x
https://en.wikipedia.org/wiki/Nonsymmetric_gravitational_theory
https://arxiv.org/abs/1512.00207

[Anonymous No.11283838]

>whats a catenoid
>are nerves neurons
>what is space
>what is a plane
>what is a line
>what is a point

[Anonymous No.11283846]

>>11283826
I was working under the assumption that [math]g[/math] is a (pseudo)-Riemannian metric, and so had to be positive definite. Interesting find with the wiki article and arxiv paper.

[Anonymous No.11283859]

>>11282692
>There's a j.
I used to hate using j for the imaginary unit in EE. Then I found out about quaternions.
>physishits BTFO

[Anonymous No.11284186]

https://doi.org/10.1145/3298689.3346997
can some1 get me this? ^^

[Anonymous No.11284192]

>>11281844
When you do stupid stuff for no reason. Just stop.

[Anonymous No.11284248]

>>11284186
Go away Susan

[Anonymous No.11284418]

Is there a self report measure along the same lines as tye BDI-II that just measures suicide risk?

[Anonymous No.11284611]

>>11268274
does anyone have a really 'mathematical' physics book? by mathematical i mean in spirit as opposed to sophistication of the actual mathematics. mainly, i want tone that has a focus on making derivations. 'just derive everything bro' is such a meme, but i dont actually see any books doing it

[Anonymous No.11284664]

>>11284611
Goldstein is like that
https://detritus.fundacioace.com/pub/books/Classical_Mechanics_Goldstein_3ed.pdf

[Anonymous No.11284690]

Hi.

I'm lost at this one.

2a^3 : 6a^2 * 6a^5

I get 1/18a^4, but I don't understand how exactly I come to get there.
Could someoin explain step by step?

[Anonymous No.11284708]

>X = current_value
>Y = highest potential value in that series.
I'm trying to return what % X is of Y, without making use of decimals.

Normally I'd divide X by Y and the remainder is the percentage, but I'm not sure how to do this with only the quotient.

[Anonymous No.11284719]

Is there a difference if I write something before or after brackets.

Example
x(3 - x)
(3 - x)x

[Anonymous No.11284727]

>>11284690
[math] 2a^3/(6a^2\cdot 6a^5)=a^{-7}/18 [/math]

>>11284719
if everything is a scalar, yes.

[Anonymous No.11284732]

>>11284727
>2a^3/(6a^2⋅6a^5)
Anon, you do the operations from left to right, it's
(2a^3 : 6a^2)*6a^ 5

[Anonymous No.11284737]

>>11284732
Does the colon represent division? then it doesn't matter. I get the same result either way.

[Anonymous No.11284739]

>>11284727
>a−7/18
Do I need to rewrite as
18/a^7? Since exponentation is negative? I hate having forgotten how to basic arithmetics and basics of algebra. I understand the more difficult stuff that is abstract just fine, but I can't do calculations for shit. I'm trying to make myself relearn and be able to do everything that is just calculations, simplification, fractions, decimals, powers, radicals and any type of factoring before this week is over, but I keep tripping up. I wish there was a linear guide for this.

t. someone trying to relearn mathematics

[Anonymous No.11284742]

>>11284732
then write your shit less ambiguous next time. if that's the case and the colon represents division, the result is [math] 2a^6 [/math]
>>11284727
should be a^-4, obv

[Anonymous No.11284752]

>>11284737
>Does the colon represent division?
I dunno lad, how did the person who asked it represent division?
>I get the same result either way.
No, you fucking don't.
>>11284742
I didn't write jack.

[Anonymous No.11284777]

hi i need to get back into math for some general gov exam
havent done math since early highschool back 10 years ago
where does the first 2n come from here?
what rule am i missing
tyty

[Anonymous No.11284788]

Are you seriously playing with this math for children ? And you even screw that ?

[Anonymous No.11284790]

>>11283471
Literal brainlet

[Anonymous No.11284791]

>>11284788
i thought it was a stupid questions thread

[Anonymous No.11284795]

>>11284777
The 2n was added best fit in purpose to prove the assumption.

[Anonymous No.11284800]

>>11284708
For those who care, I figured it out. (X*100)/Y gives the percentage and avoids floating point division.

[Anonymous No.11284833]

>>11284611
Any classical mechanics book for grad students does that.
>>11284777
[math](n+1)^2 = n^2 +2n +1 [/math].

[Anonymous No.11284837]

>tfw genuinely can't understand mathematics
>feel shame because I can't understand mathematics children learn in school
>even more shame trying to study it now after I'm an adult
I just wish my head wasn't so useless.

[Anonymous No.11285066]

>finish MA in August
>thesis advisor professor offers to work with him under an internship if I can't find work
>okay
>email him in November to see if the offer is still available, it is
>connects me with essentially the other main person I'd be working under while doing actual research
>things go well between myself and the other person as we communicate but I never hear back from my advisor this entire time
>email him today about meeting to discuss this (basically me trying to find out what I need to do to speed this along)
>tells me I need to sign up for it and need to email someone to see if I still qualify
FUCK
I'M DOUBLY ANXIOUS
WHY WOULD YOU NOT MENTION THIS AT ALL WITHIN THE PAST MONTH
WHY DID YOU WAIT FOR ME TO MESSAGE YOU BEFORE TELLING ME THIS
Am I in the wrong?

[Anonymous No.11285078]

>>11285066
you're in the wrong for being too trustful but your guy's a cunt and unprofesionnal

[Anonymous No.11285280]

If I wanted to learn physics beginning from scratch (literally from one-dimensional motion), what route would I take (self taught)? I'm going through Professor Leonard's lectures atm, and I plan on learning all of maths from him. Is there a similar course I could find on Youtube which goes from the beginning of physics all the way to advanced material, which is all taught by the same person, and they go into much detail?

Would appreciate

[Anonymous No.11285285]

>>11285280
>Is there a similar course I could find on Youtube which goes from the beginning of physics all the way to advanced material, which is all taught by the same person, and they go into much detail
probably not. there is likely no lecture that meets all this criteria.

[Anonymous No.11285328]

>>11285285
What about Khan academy's physics lectures? He covers pretty much all the basics of physics, like a high school course? I'm not looking to self-teach on a uni level, just to get really familiar with all of the fundamentals. From there on I can build using books and shit since I'll be familiar with calculus and basics of physics.

[Anonymous No.11285330]

>>11285328
You said "advanced material." If you're actually just looking for high school stuff, then khan is probably a good bet.

[Anonymous No.11285336]

(How) Is it possible to change the angle between the Sun and the axis of the Earth?
A friend told me something like, "Because the icebergs are melting, Earth's axis has shifted."
So, is it possible to change Earth's rotation in general?

[Anonymous No.11285342]

>>11285328
build knowledge*

[Anonymous No.11285345]

>>11285336
>So, is it possible to change Earth's rotation in general?
If you stand in your living you and start spinning around on your feet, you will exert net torque on the rest of the earth. It will be completely negligible, but you will "change the rotation," technically speaking.
So yes, it's just very very hard.

[Anonymous No.11285348]

>>11285330
Thanks

[Anonymous No.11285407]

Self studying spivak, and i'm slightly confused at (c). For case 2, the limit of f is 0 at 0, so can't I just use a function g that doesn't have a limit at 0 but also has the property that abs(g(x))<=M for all x like g(x)=sin(1/x)? What's the hint trying to say?

[Anonymous No.11285486]

>>11285407
>For case 2, the limit of f is 0 at 0
No it isn't, consider ya boy the Dirichlet function.

[Anonymous No.11285508]

is there a name for this relation? is there a proof for it?

[Anonymous No.11285520]

>>11285508
It's just triangle similarity.

[Anonymous No.11285561]

>>11284837
hey if you keep trying and give yourself enough time you'll get there. everyone feels dumb about what they don't know, even people that know a lot

[Anonymous No.11285563]

>>11285520
nvm I found it, it's called the geometric mean theorem

[Anonymous No.11285570]

guys please i'm freaking out i need to understand basic calculus by the end of this night and i can't do this integral, x^2 * 2^x^3

assume i'm very retarded, if anyone does end up explaining this. thank you

t. biotard

[Anonymous No.11285584]

>>11285486
Ok yeah, that's pretty silly of me. Still can't make head or tail of how to reach a solution.

[Anonymous No.11285586]

>>11285570
x^2 * 2x^3=2x^5
The derivative of that is 10x^4, by the classical rule of derivation for polynomials.

[Anonymous No.11285593]

>>11285586
it's not 2x^3, it's 2^x^3

[Anonymous No.11285600]

>>11285584
The trick is, if f is always "large enough", then we can just take the inverse, and we know it's stable.
I don't know what exactly he expects you to do for the othe one.
Possibly work with a "splitting" of the function into two parts.
>>11285593
Did you try using the product rule to split off x^2, and then use the chain rule for 2^x^3?

[Anonymous No.11285622]

>>11285600
Case 1 i've solved. It's just the second case that's bothering me, and his hint isn't helping. I might just save this problem for later, if you have no other tips, thanks anyway.

[Anonymous No.11285639]

>>11285622
Right, right.
So, we have the following possibilities:
If zero appears infinitely often, we take a function which is one where f is zero, and equals zero everywhere else.
This lets us assume that, for some epsilon, x is smaller than epsilon implies f(x) is different from zero.
Then we take the inverse function again.

[Anonymous No.11285641]

>>11285600
isn't chain rule for derivatives

[Anonymous No.11285643]

>>11285641
Oooooh, you need the integral.
Just set u=x^3.

[Anonymous No.11285651]

>>11285643
i'm trying to follow along a solution but i don't really understand exactly what dx and du are so i'm clueless as to how this step is done

[Anonymous No.11285740]

>>11285651
What I learned in physics, the du or dx is just an infinte small step of the u or x. An integral just adds areas along these small steps on the x-achsis together. So you get the amount of area under or above your graph.

As far as I know mathguys wouldn't agree and just say it marks the end of the integral.

In your case, I just would ignore the du or dx and see it as some kind of a symbol or so.

inb4 agressive mathematician

[Anonymous No.11285855]

What is the antiderivative of 4/(1+x^2) ?

I know that 1/(1+x^2) is the derivative of arctanx, but why is it that the AD of the above isn't 4x*arctanx, instead of the true answer which is 4arctanx?

[Anonymous No.11285949]

>>11285855
[math] \displaystyle\int a\cdot f(x)\,\mathrm{d}x=a\int f(x)\,\mathrm{d}x\neq ax\int f(x)\,\mathrm{d}x [/math]

[Anonymous No.11285963]

>>11284664
>>11284833
Are there any good quantum books that take a similar approach?

[Anonymous No.11286157]

Can someone point me to a good resource for Boolean algebra properties? I tried to prove to myself that two logic functions were the same and ended up with gibberish when I tried to do it algebraically. I resorted to constructing truth tables and comparing them.

The logic functions in question are both supposed to represent an xor gate with one being z=xy'+x'y and the other being z=(xy)'(x+y). I tried rewriting and manipulating them with the notation and rules on Wikipedia, but I must have applied them wrong.

https://en.m.wikipedia.org/wiki/Boolean_algebra

[Anonymous No.11286453]

>>11285949
what if it was sinx in the numerator? Would it then be -cosxarctanx?

[Anonymous No.11286468]

>>11286453
No. Product rule.

[Anonymous No.11286678]

>>11286157
z = (xy)'(x+y)
= (x'+y')(x+y)
= (x'(x+y)+y'(x+y))
= (x'x+x'y)+(xy'+yy')
= x'y+xy'

[Anonymous No.11286917]

>>11284664
ty anon

[Anonymous No.11286987]

Is studying Lang's Intro To Calculus enough to get a grasp of calculus for an undergraduate physics course?

[Anonymous No.11287071]

>>11286678
Thanks