[ 3 / biz / cgl / ck / diy / fa / g / ic / jp / lit / sci / tg / vr / vt ] [ index / top / reports / report a bug ] [ 4plebs / archived.moe / rbt ]

Due to resource constraints, /g/ and /tg/ will no longer be archived or available. Other archivers continue to archive these boards.Become a Patron!

# /sci/ - Science & Math

[ Toggle deleted replies ]
File: 350 KB, 368x450, 1591885923916.gif [View same] [iqdb] [saucenao] [google] [report]

I need help with this shit
AX = I − 3X AX + 3X = I (A + 3I)X = I X = (A + 3I) ^−1

In AX + 3X = I (A + 3I)X = I How come there's two I? And how did one of these get next to the 3?

And in (A + 3I)X = I X = (A + 3I) ^−1 one of the I disappears, what's up with that?

 >> Anonymous Fri Aug 28 14:12:38 2020 No.12058495 >>12058471There we go
 >> Anonymous Fri Aug 28 15:29:25 2020 No.12058764 >>12058471>In AX + 3X = I (A + 3I)X = I How come there's two I? And how did one of these get next to the 3?I'm assuming these are matrices. You can multiply a matrix by another matrix, you can multiply a matrix by a scalar, you can add matrices, you can add scalars, but you can't add a scalar to a matrix. So you can't factor AX+kX as (A+k)X, but you can use X=IX and associativity to write kX = k(IX) = (kI)X and thus AX+kX = AX+(kI)X = (A+kI)X.
 >> Anonymous Fri Aug 28 17:24:35 2020 No.12059172 If you drop an object from the height of 20m, how fast will it be when it hits the ground and how long does it take to hit the ground?How do you calculate it?
 >> Anonymous Fri Aug 28 18:24:37 2020 No.12059481 >>12059172Assuming the initial velocity is zero, the velocity v after time t is equal to acceleration a multiplied by time t: v=a*t. The average velocity over that interval is half that: (1/2)*a*t. The displacement (change in position, distance moved) s is equal to average velocity multiplied by time: s=(1/2)*v*t=(1/2)*a*t^2.So you have four quantities: acceleration, time, final velocity, displacement. Given two, you can solve for the other two.Given acceleration and displacement, s=(1/2)*a*t^2 => t=sqrt(2*s/a). If accelerating under (Earth) gravity, acceleration is 9.81 m/s^2; so for s=20 m, t=sqrt(2*20/9.81)=2.02 seconds. Final velocity v = a*t = a*sqrt(2*s/a) = sqrt(2*a*s) = sqrt(2*20*9.81) = 19.8 m/s.
 >> Anonymous Fri Aug 28 20:57:48 2020 No.12060791 https://projecteuler.net/problem=371"whats the expected number of plates to see for a win"I don't know how to interpret this. I know its not the same as 'whats the minimum number of plates to see to guarantee a win'. Does this somehow relate to the function that takes the number of plates he saw and returns the prob he won?
 >> Anonymous Fri Aug 28 20:59:29 2020 No.12060799 >>12060791how many randomly-chosen 3 digit integers do you need for the sum to be over 1000, on average
 >> Anonymous Fri Aug 28 21:03:32 2020 No.12060814 >>12060799I dont think you read the question very carefully since you said 'over 1000'. lets me ask the same question, but lets also make the assumption that the letters are not there. What *precisely* does 'expected number for a win mean'?
 >> Anonymous Fri Aug 28 21:05:10 2020 No.12060819 >>12060814Does this mean, if we consider all possible subsets of license plates that win the game, what is the average size?
 >> Anonymous Fri Aug 28 21:05:15 2020 No.12060821 >>12060814okay then change my answer to be "exactly 1000" retard. expected number for a win means 1/p, where p is the probability that two randomly-chosen 3 digit integers add to exactly 1000
 >> Anonymous Fri Aug 28 21:08:19 2020 No.12060838 >>12059172Look up the SUVAT equations (also known as the UVAST equations). They relate displacement (S); initial velocity (U); final velocity (V); acceleration (A); and time (T) for an object moving in a straight line with constant acceleration. Given any 3 of these variables, you can calculate the other 2 using these equations. In the case of your question, you have the initial speed; displacement; and acceleration.
 >> Anonymous Fri Aug 28 21:11:02 2020 No.12060844 >>12060799$\left\lceil\frac{1000}{\frac{999}{2}}\right\rceil$Not that deep bro.Not that deep bro.
 >> Anonymous Fri Aug 28 21:29:32 2020 No.12060892 >>12060821as you might be able to verify, the question as you phrased it is trivial, so it is not likely to be the solution to the project euler problem.Ironic that you call me a retard when, even when you look at the problem again, you still don't even grasp the question.I'm fairy certain my interpretation >>12060819is correct. You have a really shitty attitude, and you come across as a pathetic nerd
 >> Anonymous Fri Aug 28 21:34:21 2020 No.12060900 >>12060892actually, i reviewed a similar q on stack exchange and the phrase does seem to mean inverse of probability. still not calculated the way you said it was.
 >> Anonymous Fri Aug 28 22:29:34 2020 No.12061005 >>12060791Expected value is the probability equivalent of the arithmetic mean in statistics.[eqn]\sum_{i=1}^\infty i\,P(i)[/eqn]where P(i) is the probability that a win occurs after exactly i plates.P(0)=0, P(1)=0, P(2)=999/10^6 (the first plate can be anything except 000, the second must be 1000 minus the first). Also bear in mind that P(i) is bitonic; it starts small, increases with the total number of plates seen, then decreases due to the requirement that he saw i-1 plates without a win. As the various P(i) are mutually exclusive, they sum to 1, so P(i)<1-P(1)-P(2)-...-P(i-1).
 >> Anonymous Fri Aug 28 23:24:58 2020 No.12061133 File: 216 KB, 800x600, 1529308172362.png [View same] [iqdb] [saucenao] [google] [report] Here is my question.Yesterday I took a laxative type thing and shit 5 times within the morning, essentially emptying my intestines. The rest of the day I barely ate, maybe less than 1000 calories of food.Today I wake up, and once again, my intestines are full of poop. I can literally feel it bulging from belly. I dont understand where all this shit is coming from. So why does this happening? Where is the shit coming from?
 >> Anonymous Sat Aug 29 00:04:08 2020 No.12061195 >>12058471How to become omniscient AI that transcends existence
 >> Anonymous Sat Aug 29 00:50:05 2020 No.12061255 >>12058471Is this real?
 >> Anonymous Sat Aug 29 05:58:55 2020 No.12061976 >>12060819All possible minimal subsets that win the game. ie. you stop immediately upon winning the game so (500, 500) exists but (500, 500, 1) doesn't. If you simulate it you get like 40 with a standard deviation of 20 but Project Euler probably wants you to enumerate all the outcomes up to some symmetry and get it precisely.
 >> Anonymous Sat Aug 29 06:28:52 2020 No.12062036 stupid questions? i have one. i know fuck all about maths but this thaught occured to me.Infinity isnt a number. right? there are an infinite number of numbers sure, but thet fact or the symbol used for it isnt a number.whatever number you can concive of, you can just add one, but that will still just be a number, you will never reach infinity.or is this just semantics? even in a dumb questions thread this feels dumb
 >> Anonymous Sat Aug 29 11:04:50 2020 No.12062558 File: 2 KB, 300x300, 10 years in paint.png [View same] [iqdb] [saucenao] [google] [report] how do i find the spatial angle(solid angle?) of this circle
 >> Anonymous Sat Aug 29 12:21:39 2020 No.12062762 >>12062558The solid angle of a cone with half-angle θ is 2π(1-cos θ). Here, cos θ = 1/√2, so 2π(1-1/√2) ~= 1.84 sr.
 >> Anonymous Sat Aug 29 12:29:21 2020 No.12062784 >>12062036> Infinity isnt a number. right?Right. If you extend the reals to include infinity, you can define x/0=∞ for all x≠0, but then you still have several expressions which are undefined, including ∞.0 and ∞-∞.
 >> Anonymous Sat Aug 29 12:53:40 2020 No.12062867 >>12060819It's not about "subsets", because order matters. For [1,500,500] and [500,1,500] the number of plates seen is 3 but for [500,500,1] it's 2.So you're dealing with conditional probabilities: the probability of a win after n plates is the probability that a sequence of n plates includes a 1000-sum pair, given that the initial n-1 plate subsequence doesn't.IOW, the nth plate must make a 1000-sum pair with at least one plate from the initial n-1 plates, but no two plates within the initial n-1 plates make a pair. If the initial n-1 plates are all distinct, the probability of the nth plate forming a pair with one of them increases but so does the probability that a pair already exists. If the initial n-1 plates contain many duplicates, it's less likely that they contain a pair but also less likely that the nth plate will form a pair.The main symmetry is that you don't particularly care exactly which numbers are present in the initial n-1 plates (other than 000, which will never form a pair with another plate), only the probability that n-1 plates will contain k distinct, non-zero numbers.From the probability of n plates having k distinct numbers, you can determine the probability of n-1 plates containing no pairs and the probability of the nth plate forming a pair. For the latter: if there are k distinct numbers, there's a k/1000 probability that the nth plate will be a duplicate, a (k-1)/1000 probability that it will be distinct and non-zero, and 1/1000 that it will be zero. If it's distinct and non-zero, the probability of it forming a pair is k/999 if none of the k are zero and (k-1)/999 if one of them is zero. There's a k/1000 probability that one of the k is zero.
 >> Anonymous Sat Aug 29 14:52:44 2020 No.12063213 Are Integrals the inverse of Derivatives? how difficult is to learn integrals? i know derivatives but not integrals and i'm seeing that scary integral sign and it seems like hell
 >> Anonymous Sat Aug 29 15:05:20 2020 No.12063261 One of the examples in this analysis text book has the following and I'm a bit confused on how they managed to get from the first line to the second line.$\textrm{Let} \ \epsilon = \frac{|x|}{2} > 0, \textrm{then} \ |x_n - x| < \frac{|x|}{2} \\ x_n < \frac{|x|}{2} <0$
 >> Anonymous Sat Aug 29 15:19:31 2020 No.12063312 >>12063261This is clearly self contradictory.
 >> Anonymous Sat Aug 29 15:21:40 2020 No.12063323 >>12063213Integral calculus is way way harder than differential. It basically combines all your knowledge like complex numbers, differential calculus, trigonometry, algebra, geometry and mixes it up in one big chapter. Be prepared for something challenging.
 >> Anonymous Sat Aug 29 15:29:21 2020 No.12063360 >>12063312It's a proof by contradiction. The goal was to show that $0 < 0$ which gives us a contradiction.
 >> Anonymous Sat Aug 29 15:33:05 2020 No.12063372 What do you call that thing where you feel the need to do something to completion? An example would be a book that you don't like - what would you call an moment where you simply feel the need to finish it, to the point where you can't really calm down until you finish it because it just stays in the back of your head, annoying you?You don't like the book, you don't want to read it, it's boring, but you feel you HAVE to read it until the end.
 >> Anonymous Sat Aug 29 15:46:14 2020 No.12063418 >>12063261>3I would assume it's because x_n is some type of convergent sequence to x, so that for all epsilon (or equivalently 2*epsilon since these are 1-1 mappings with the positive reals and so include all of it so that the quantifier requirements are the same), so that |x_n-x|
 >> Anonymous Sat Aug 29 15:52:45 2020 No.12063447 Does anyone have any good textbook recommendations for optical/atomic clocks? Bored out of my mind.
 >> Anonymous Sat Aug 29 16:28:11 2020 No.12063612 What's the difference between opposite and inverse in math?
 >> Anonymous Sat Aug 29 16:32:25 2020 No.12063629 >>12063612An opposite of $x$ is $\exists y$ such that $x+y=0$. An inverse of $x$ is $\exists y$ such that $x*y=e$, where $*$ is an arbitrary binary operation and $e$ is the identity element of the given set.
 >> Anonymous Sat Aug 29 16:50:24 2020 No.12063693 File: 72 KB, 1261x663, unknown (1).png [View same] [iqdb] [saucenao] [google] [report] Can someone help explain how the person solved the problem? We're using different numbers but the wavelength on my end is 0.5 instead 0.405.Why did they derive the displacement function? Why does the slope matter?Originally, I had inputted 0.5 into the system because the amplitude seemingly reached 0.5 and -0.5 but it was wrong.
 >> Anonymous Sat Aug 29 17:03:37 2020 No.12063742 if time is a scalar then $t_0$ (when talking about $\Delta t$) will always be 0, right?
 >> Anonymous Sat Aug 29 17:15:45 2020 No.12063793 >>12063742what? definitely need more context because as you've formulated it the answer is no
 >> Anonymous Sat Aug 29 17:18:07 2020 No.12063803 >>12063693The fact that it's a travelling wave (dependent upon t) is irrelevant to the problem. At any given t, you have a sinusoidal curve, y(x)=ym*sin(2πx/λ+φ), where ym is the amplitude, λ is the wavelength, φ is the phase. Its slope at any given x is dy/dx = (2π/λ)*ym*cos(2πx/λ+φ). The maximum slope is sm=(2π/λ)*ym. Solving for ym gives ym=sm*(λ/2π). For sm=0.5 and λ=0.5 m => ym=3.98 cm.
 >> Anonymous Sat Aug 29 17:23:23 2020 No.12063824 >>12063803Oh fuck, thank you anon. I got tripped up by the slope-position graph and it threw me into a spiral of confusion. Thank you again anon!
 >> Anonymous Sat Aug 29 17:25:09 2020 No.12063832 Are magnesium supplements really as useful as people make them out to be? I found out that I'm basically magnesium deficient as fuck and will probably need them.
 >> Anonymous Sat Aug 29 17:27:32 2020 No.12063837 >>12063832what kind of a question is this?if you're deficient of a certain nutrient, then of course supplements are useful
 >> Anonymous Sat Aug 29 17:43:47 2020 No.12063895 >>12063837>what kind of a question is this?A stupid one. Didn't you read the thread name?
 >> Anonymous Sat Aug 29 18:15:35 2020 No.12063975 >>12063837>>12063895Yeah that was unironically pretty dumb of me. Thanks anyway bros.
 >> Anonymous Sat Aug 29 18:18:48 2020 No.12063981 >>12063975Better to be unironically dumb than ironically dumb.
 >> Anonymous Sat Aug 29 18:34:20 2020 No.12064030 Isn't the limit of (sin t)/t as t->0 undefined? Because you cannot divide by 0 if you plug in 0 for t in the denominator?
 >> Anonymous Sat Aug 29 18:42:29 2020 No.12064045 >>12064030$\sin t$ also goes to 0, so you get $\frac{0}{0}$, which is the whole point of doing limits.
 >> Anonymous Sat Aug 29 18:43:22 2020 No.12064047 >>12064030l'hospital
 >> Anonymous Sat Aug 29 18:43:57 2020 No.12064051 >>12064047>>12064045AAAAAAAAAAAAAAAAAAAAAAAAAAAH, I remember now, the semester just started so I'm getting a bit rusty.
 >> Anonymous Sat Aug 29 18:44:24 2020 No.12064053 >>12064051Cheers, lad.
 >> Anonymous Sat Aug 29 18:59:10 2020 No.12064104 >>12064030No. sin(t)/t itself is undefined at t=0, the limit is equal to 1. For 0 1-(1/6)t^2 0<1-sin(t)/t<(1/6)t^2 => |sin(t)/t-1|<(1/6)t^2. Thus for any ε>0, you can find some value τ s.t. |sin(t)/t-1|<ε for all 0
 >> Anonymous Sat Aug 29 19:08:03 2020 No.12064131 I have a stupid question.So my homework is worth 10% of my total grade and that for every homework that is "late", I get 10% taken off of that homework, so if I'm late on every homework but I complete them, then in total the homework accounted for 9% of my grade right?
 >> Anonymous Sat Aug 29 19:08:33 2020 No.12064134 >>12064131yes
 >> Anonymous Sat Aug 29 19:09:34 2020 No.12064139 >>12064131well wait no you have a missing 1% of your grade that's a guaranteed 0.
 >> Anonymous Sat Aug 29 19:46:16 2020 No.12064252 What are common errors brainlets (like myself) make with kalman filters? I am tracking objects on a 2d plan with x and y both having baby physics motion equation on them. I get 70-80% accuracy. I need more.
 >> Anonymous Sat Aug 29 23:42:18 2020 No.12064836 >>12063612"opposite" doesn't have any specific meaning
 >> Anonymous Sun Aug 30 00:05:55 2020 No.12064870 >>12058471Bros pls help I'm completely lost with this one.Given $f(x) = e^x +5\sin (x) - 2$ prove that the equation $f(x) = 0$ has a single root in $(0,3/2)$ , find bounds for $|f'|$ and $|f''|$ in order to find a $x^{(0)} \in (0,3/2)$ such that the Newton rhapson method converges to the root f has in the interval. Also find the order of comvergence
 >> Anonymous Sun Aug 30 00:36:33 2020 No.12064934 >>12064870Intermediate Value Theorem plus monotonicity of f on (0, pi/2), the rest should be pretty simple once you have the bounds, it's been a while since I've taken numerical analysis.
 >> Anonymous Sun Aug 30 01:07:36 2020 No.12064990 >>12064934can you pls expand a bit more on this? also, its (0,3/2) not (0,pi/2) I think it mostly has to do with the theorem that states that if you have a strictly convex function on I then given some conditions are met you can assert the root exists and so on, the problem its, f does not seem to be strictly convex on f
 >> Anonymous Sun Aug 30 01:11:35 2020 No.12064995 >>12064990i mean the intermediate value theorem part is clear, the rest not so much
 >> Anonymous Sun Aug 30 01:26:15 2020 No.12065016 >>12061133Laxatives mainly affect the large intestine, so the food in your small intestine isn't affected by it. Drink some water and electrolytes.
 >> Anonymous Sun Aug 30 01:51:28 2020 No.12065068 >>12064995use the intermediate value theorem coupled with the fact that the function is strictly increasing on the interval 0,3/2.since it goes from negative to positive you know it must cross 0, and since it is continuous and only increasing you know it can only cross 0 once
 >> Anonymous Sun Aug 30 01:59:01 2020 No.12065079 >>12064990f is continuous, $f(0)= -1<0,\ f(\pi/2)=e^{\pi/2}+3>0$, so by the IVT $f(x)=0$ has at least one solution in $(0, pi/2) [\math]. [math] f'(x) = e^x + 5 \cos x > 1 \text{ on } (0, \pi/2)$ since cosine is positive on that interval, so f is strictly monotonically increasing on $(0, \pi/2)$, ie. there exists a unique $c \in (0, \pi/2) \text{ such that } f(c) = 0 [\math].  >> Anonymous Sun Aug 30 02:00:40 2020 No.12065081 >>12065079yes it's stupid that /math needs the opposite slash direction as typical latex commands  >> Anonymous Sun Aug 30 02:01:10 2020 No.12065085 >>12065079Can you just us \text instead of \textrm?  >> Anonymous Sun Aug 30 02:06:05 2020 No.12065093 >>12064990fucked up tags, here we go again.f is continuous, [math] f(0)= -1 < 0,\ f(\pi/2) = e^{\pi/2} + 3 > 0$, so by the IVT $f(x)=0$ has at least one solution in $(0,\pi/2)$.$f(x)=e^x + 5\cos x > 1 \text{ on } (0,\pi/2)$ since cosine is positive on that interval, so f is strictly increasing on $(0,\pi/2)$, ie. there exists a unique $c \in (0, \pi/2) \text{ such that } f(c) = 0$.I used the interval bounded by pi/2 because it arose more naturally than 3/2.
 >> Anonymous Sun Aug 30 02:13:39 2020 No.12065109 File: 307 KB, 1282x1640, Screen Shot 2020-08-29 at 11.12.40 PM.png [View same] [iqdb] [saucenao] [google] [report] >>12065081yes its enraging >>12065085there are some subtle differences between the two in  math mode, I usually stick to \textrm but apparently \text works fine here.take a differential geometry class if you really wanna blow your brains out latexing.
 >> Anonymous Sun Aug 30 04:04:43 2020 No.12065283 >>12065093Lmao bro is (0,3/2) not (0,pi/2).Yeah I figured out the rest, basically you get that:[eqn]|r - x_{0}| < \frac{|2f'(r)|}{|f''(r)|}[/eqn]So you just maximize f' and minimize f" and get your appropriate bounds like so
 >> Anonymous Sun Aug 30 07:46:18 2020 No.12065721 I've not had to do algebra/complex numbers in years and I'm really out of practise. Is there a good website for getting examples so I can get back into shape?
 >> Anonymous Sun Aug 30 07:50:18 2020 No.12065730 i'm literally mentally retarded when it comes to mathematics and fail to grasp the function of the majority of the maths tought to me throughout my life. I suspect i already know the answer to this question but is the majority of mathematics just abstract fuckery with no realworld applications or am i a complete mong.Obviously i understand that coding is pretty much only possible because of abstract math.
 >> Anonymous Sun Aug 30 12:05:58 2020 No.12066367 File: 27 KB, 700x467, 1583878742628.png [View same] [iqdb] [saucenao] [google] [report] >>12065721>>12065721Maybe check out the Khan Academy: www.khanacademy.org/mathThere's quite a lot of algebra on there and the Precalculus section has complex numbers
 >> Anonymous Sun Aug 30 12:11:16 2020 No.12066386 >>12065995$1 + \frac{1}{3} = \frac{3}{3} + \frac{1}{3} = \frac{4}{3} = 1 \div \frac{3}{4}$
 >> Anonymous Sun Aug 30 12:28:57 2020 No.12066434 >>12065995i've read your post twice and still dont understandwhat you're discovering is a 10% reduction, then a 10% increase doesnt end up at the starting value?
 >> Anonymous Sun Aug 30 12:35:25 2020 No.12066454 >>12066386Of course. Seems pretty obvious now. How did the manual manage to get it wrong though? >>12066434Planned gas = 1440 liters. The most common reserve in tec diving is a 1/3 reserve, so you want to add 1/3 reserve gas to your planned gas.My problem is that the formula the manual recommends seems to add 1/2 instead.
 >> Anonymous Sun Aug 30 12:40:36 2020 No.12066476 >>12066454>How did the manual manage to get it wrong though?Maybe someone got confused and thought "add one-third extra to the tank as a reserve" and "one-third of the total in the tank is the reserve"
 >> Anonymous Sun Aug 30 12:42:14 2020 No.12066481 >>12066476Oops that "and" should be "meant"
 >> Anonymous Sun Aug 30 12:53:01 2020 No.12066524 >>12066476Intriguing. That seems possible. I was thinking they likely just started out with percentages and just assumed they got it right.
 >> Anonymous Sun Aug 30 13:01:58 2020 No.12066568 File: 68 KB, 787x619, file.png [View same] [iqdb] [saucenao] [google] [report] what are the alpha and beta phases on the left and right?
 >> Anonymous Sun Aug 30 14:16:00 2020 No.12066926 anyone have a link for a working latex preview greasemonkey script? old one doesn't seem to work.
 >> Anonymous Sun Aug 30 15:08:26 2020 No.12067111 >>12065283>Lmao bro is (0,3/2) not (0,pi/2).π>3 => π/2>3/2 => (0,3/2)⊂(0,π/2)So proving that f'(x)>0 for x∈(0,π/2) proves that f'(x)>0 for x∈(0,3/2). f'(x)>0 means that there cannot be more than one root (monotonicity).For proving that there's at least one root, the range needs to be smaller. You can just evaluate f(3/2) with a calculator to get ~7.5, but "calculator says ..." tends to be frowned upon in proofs.For that, consider π<4 => π/4<1<3/2, f(π/4)=e^(π/4)+5*sin(π/4)-2 = e^(π/4)+5/√2-2 > 1+2-2 = 1 > 0 (as e^(π/4)>1, sin(π/4)=1/√2, 5*sin(π/4)=5/√2 > 4/√2 = 2√2 > 2). f(0)<0, f(π/4)>0 => f(x) has at least one root in (0,π/4) and thus in (0,3/2).The hard part is showing convergence. I know that the basin of attraction relates to f, f' and f'' but I don't remember the details. Basically you need to ensure that the intercept of the tangent with f=0 doesn't leave the basin of attraction.
 >> Anonymous Sun Aug 30 15:39:36 2020 No.12067194 File: 14 KB, 966x115, unknown.png [View same] [iqdb] [saucenao] [google] [report] Ok can someone give me some hints and formulas to use? The semester just started but the homework expects us to remember everything last semester (I spent most of summer dealing with the coronavirus and those close to me who got it so I didn't have time to review) so I'm really rusty and just needs a heads-up on how to approach this question.
 >> Anonymous Sun Aug 30 15:52:53 2020 No.12067233 >>12067194$v \cdot a = ||v|| \ ||a|| \cos(\theta)$ where theta is the angle between the two vectors. That's a dot product if it's not clear.
 >> Anonymous Sun Aug 30 15:54:00 2020 No.12067237 >>12067194the derivative of position is velocitythe derivative of velocity is accelerationthen use >>12067233
 >> Anonymous Sun Aug 30 15:55:55 2020 No.12067243 >>12067233>>12067237So I have to differentiate r(t) twice for v(t) and a(t) and then dot product them (v and a) right? And then the ||v|| and ||a|| is where I square their components and then root them so that I can add them into a single number? Thank you both so much! I hope that I don't fall behind this semester like last semester!
 >> Anonymous Sun Aug 30 15:57:11 2020 No.12067247 >>12067243yes that's right
 >> Anonymous Sun Aug 30 16:15:30 2020 No.12067339 File: 58 KB, 950x1130, Screen Shot 2020-08-30 at 3.15.00 PM.png [View same] [iqdb] [saucenao] [google] [report] >>12067243Always think of the dot product geometrically.
 >> Anonymous Sun Aug 30 17:17:51 2020 No.12067549 File: 15 KB, 964x101, unk.png [View same] [iqdb] [saucenao] [google] [report] Just for clarification, they want me to differentiate the position vector r(t) for the velocity vector and then find the parametric equations for the velocity vector (x= and y=) then plug in $t_0 = \frac{3pi}{2}$ right? The 'tangent line to a smooth curve.... etc' has me very confused so this is what I understood from it.
 >> Anonymous Sun Aug 30 17:19:08 2020 No.12067560 >>12058471What is the opposite of a bijective function? A hash function, or using modular arithmetic accomplishes this, but is there a more general term for this?
 >> Anonymous Sun Aug 30 17:57:07 2020 No.12067671 >>12067560>What is the opposite of a bijective function?A non-surjective and non-injective function.>but is there a more general term for this?No.
 >> Anonymous Sun Aug 30 18:04:51 2020 No.12067713 >>12067560>>12067671Just to be safe, if you are reading "opposite" as not, so "opposite of bijective" is "not bijective," then its either not injective or not surjective. Doesn't need to be both.
 >> Anonymous Sun Aug 30 18:10:05 2020 No.12067730 >>12067713Yeah, I'm trying to use a non-bijective function for something, but searching for that just gives you bijective functions. Wasn't sure if there was a better term to search. Hash functions work but I wanted to see if there were other options.
 >> Anonymous Sun Aug 30 18:10:44 2020 No.12067731 File: 5 KB, 300x175, opamp.png [View same] [iqdb] [saucenao] [google] [report] what happens if i switch around the positive and negative inputs on this circuit? does it just break?
 >> Anonymous Sun Aug 30 18:10:57 2020 No.12067734 >>12067549nvm I got it!
 >> Anonymous Sun Aug 30 18:14:38 2020 No.12067747 >>12067339The inner product is algebraically defined
 >> Anonymous Sun Aug 30 18:19:22 2020 No.12067769 >>12067731If you mean the power lines, then it won't work. If you mean the two inputs, you'll just have the circuit ramp up to Vdd. You're just giving positive feedback
 >> Anonymous Sun Aug 30 18:41:42 2020 No.12067849 >>12067769that's what i thought; I only know how to do virtual ground analysis so eh. is there a way i can actually show it'll blow up to Vdd if the inputs were swapped?
 >> Anonymous Sun Aug 30 18:50:21 2020 No.12067883 File: 5 KB, 514x53, unknown (1).png [View same] [iqdb] [saucenao] [google] [report] Okay how do I do this? I know that to get the tangent line, I should first differentiate the position vector to get the velocity vector but then at that point I'm lost :o
 >> Anonymous Sun Aug 30 18:55:12 2020 No.12067899 >>12067883differentiate to get the slope m. don't think of it as a velocity vectorthen you use the point given to solve for intercept b of the function tangent=m*r+b since you know the tangent has to equal the original function at the point where they touch.
 >> Anonymous Sun Aug 30 19:04:19 2020 No.12067938
 >> Anonymous Sun Aug 30 19:05:25 2020 No.12067944 >>12058471howe to handle being both smart and dumb at the same time?Realizing its all pointless as death solves all problems but the human animal wants to fulfill the 3Fs, none of winch can ever be fulfilled adequately because being sapient is a curse?>tl;dnrNever smart, no aware, enough to have money to solve problems, never dumb enough to enjoy existence?
 >> Anonymous Sun Aug 30 19:08:50 2020 No.12067958 >>12067899Thank you! This question got me super confused lol.
 >> Anonymous Sun Aug 30 19:13:30 2020 No.12067989 Uni of St Andrews worth the international fees? I'm from South America and want to move to Europe. I can either do a bachelor at home country for half the St Andrews fee and then try to apply for Master's or a job in Europe, or take my offer and move directly there for Bachelors but paid like 30k pounds a year. Which do you think is the smartest choice? Does St Andrews have enough prestige to warrant that huge tuiton fee?
 >> Anonymous Sun Aug 30 19:24:27 2020 No.12068065 File: 110 KB, 849x565, Americhad.jpg [View same] [iqdb] [saucenao] [google] [report] >>12067989Why not just come up to your northern brother?
 >> Anonymous Sun Aug 30 19:30:19 2020 No.12068112 >>12067989if you want to stay in Europe I'd recommend just going there for undergrad. I have to imagine that would make everything after it so much easier.
 >> Anonymous Sun Aug 30 19:47:00 2020 No.12068214 >>12067730A hash function can be bijective if the data being hashed is the same size as the hash. E.g. CRC32 applied to 32-bit integers is bijective (similarly for other CRC hashes).
 >> Anonymous Sun Aug 30 21:10:47 2020 No.12068466 File: 7 KB, 100x381, sbr.png [View same] [iqdb] [saucenao] [google] [report] I've got this spreadsheet full of data, it has 3 datapoints: s, b and r.s and b are plugged into a script (which takes a long time to run and I don't have the source code for) and produce r, the same s and b values don't always produce the same r but they're fairly close to each other. How would I go about converting this data into a formula which estimates the value of r when given an s and b value?
 >> Anonymous Sun Aug 30 21:13:07 2020 No.12068471 >>12068466>same s and b values don't always produce the same rhow does this happen, are there other variables that you simply don't know?just do a multidimensional curve fit
 >> Anonymous Sun Aug 30 21:19:56 2020 No.12068487 >>12068471>how does this happen, are there other variables that you simply don't know?My best guess is that the script is making its own estimations about the expected result and padding the result with null data because a bit of overhead is better than repeating the process to get rid of it considering how long it takes to run - I'm in the same boat and trying to work out a way to predict whether the input values will go over the r limit so I can make it refuse to run instead of wasting execution time>just do a multidimensional curve fitThanks lad
 >> Anonymous Sun Aug 30 22:01:02 2020 No.12068582 File: 29 KB, 1390x110, Screen Shot 2020-08-30 at 9.00.07 PM.png [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Sun Aug 30 22:15:57 2020 No.12068615 >>12068582based and pughpilled
 >> Anonymous Sun Aug 30 23:41:11 2020 No.12068851 >>12068582Define f(x) = 0 on the irrational numbers. Make f(x) = 1 on the integers. Make f(x) = 2 on multiples of 1/2 take away integers. Make f(x) = 3 on multiples of 1/3 take away whats defined before. Continue this process.
 >> Anonymous Mon Aug 31 00:04:52 2020 No.12068878 >>12068851Bless you, anon.
 >> Anonymous Mon Aug 31 00:14:56 2020 No.12068897 File: 10 KB, 266x182, download.jpg [View same] [iqdb] [saucenao] [google] [report] How do I find out just by looking at the structure of a chemical, the difference between polarity? For example, take leucine and proline. How am i meant to know Proline is more polar than Leucine?
 >> Anonymous Mon Aug 31 00:27:45 2020 No.12068925 >>12068897because look at the "side chains," highlighted in green. a bunch of carbons isn't polar, but a nitrogen in a ring is because the electrons really don't want to be in a 5-member ring
 >> Anonymous Mon Aug 31 01:05:45 2020 No.12068992 Consider the equation: [eqn]f(x) = \sin (x) - \ln (x) = 0[/eqn]Using a numerical method, we find that the solution is $x \approx 2.219107$ we can aproximate this solution further and further, now, the question is, is this $x$ irrational? can we prove it to be irrational?
 >> Anonymous Mon Aug 31 01:56:59 2020 No.12069061 >>12068992That is almost certainly a transcendental number, however proving that is a different matter entirely. It took until the 18th century to prove that $\pi$ was irrational and the 19th century to prove that it was transcendental. Despite there being an uncountably infinite amount of them, they are extraordinarily hard to prove.
 >> Anonymous Mon Aug 31 02:12:28 2020 No.12069092 >>12069061Yes, exactly, its insanely hard to prove but seems to be irrational at the very least
 >> Anonymous Mon Aug 31 03:50:39 2020 No.12069234 https://en.wikipedia.org/wiki/Squared_triangular_number#History>Nicomachus, at the end of Chapter 20 of his Introduction to Arithmetic, pointed out that if one writes a list of the odd numbers, the first is the cube of 1, the sum of the next two is the cube of 2, the sum of the next three is the cube of 3, and so on.Am I missing something, or is that not just squares and not cubes?
 >> Anonymous Mon Aug 31 04:32:34 2020 No.12069284 How do I calculate the probability of something being close to 100%? Say I have 9000 unique cards and I want to be able to see every card at least once. I can only ever see 5 cards at one time before putting them back in the 9000 unique card 'deck' and 'shuffling' before drawing 5 cards again. Basically, grab 5 random cards from the entire 9000 cards. With each iteration, there must be a way to know if you've gone through so-and-so many unique cards right? For example, if I'm on the 600th iteration. I've gone through 3000 cards. How do I know what the likelihood that each of those 3000 cards is unique? How many iterations would I have to go through to be sure I'll get a high certainty of having seen all the 9000 unique cards (90-100%)? Obviously 1800 iterations would be the lowest possible amount to have seen each unique card at least once, but I don't get how you find the next sets of information.
 >> Anonymous Mon Aug 31 06:06:39 2020 No.12069411 Wasn't sure what board to ask this in. Sorry if it doesn't belong here.Are humans the only species with a fear of extinction (as a species, not individuals)? It just dawned on me how relatively popular the concept of 'extinction of the human race' is on fiction. The heroes have to save humans from an asteroid, from aliens, from a plague, from a super-villain that wants us all dead.Is this something that bothers other creatures? It seems like most only care about themselves and possibly other tribal/colony members, with the sporadic creature saving the life of an organism of a different species (a dolphin saving a human and the like).Is it even instinctual? I'm not sure humans from 20,000 years ago would have this fear. Seems to be modern. Of course, people from that time didn't know how the limits of the world, or how many humans there were, or that there were things that could wipe them all. But even if so, I'm not sure they would care. For that to happen, they would need to consider people from across the globe their fellow man, but they didn't even like the tribe a few miles along the river.Then again there are ancient religious texts of all humans being wiped out so maybe they would care.Is this, thus, a fear that has appeared as a consequence of our understanding of the fragility of a species us a whole, as well as an increase of empathy in other humans, no matter how distant and different?Or is it a fabrication of fiction, that people have accepted as their own?If a shark doesn't care if 90% of the sharks in the world died tomorrow, why should we care if the same happened to humans?
 >> Anonymous Mon Aug 31 08:21:52 2020 No.12069611 I just did the mensa online test for my country (Germany) and it says I could potentially be suited for mensa. Is it worth the effort and money to go there and take an actual IQ test? I don't even know what the advantages of being a mensa member would be and I don't know how realistic it is that I actually have the required IQ. Oh and how can I do this without coming off as arrogant to my parents, with whom I still live (fuck rent)?
 >> Anonymous Mon Aug 31 08:38:27 2020 No.12069639 File: 37 KB, 626x626, thinking.jpg [View same] [iqdb] [saucenao] [google] [report] how can we define time? 4th dimention?
 >> Anonymous Mon Aug 31 11:41:36 2020 No.12070056 >>12069639Take $\mathbb{R}^n$ and set $n=4$.
 >> Anonymous Mon Aug 31 12:40:55 2020 No.12070288 File: 30 KB, 541x263, constant vector.png [View same] [iqdb] [saucenao] [google] [report] can someone explain was they mean by "constant vector" for a?I cannot start question 19 because I don't know what they mean by that
 >> Anonymous Mon Aug 31 12:52:56 2020 No.12070343 How do I find the singularities of a function?
 >> Anonymous Mon Aug 31 12:55:32 2020 No.12070354 >>12070288A vector that doesn't change directions with respect to any variable. $(2,4,3),(0,0,0), (8483209,848302948)$ would all be constant vectors.
 >> Anonymous Mon Aug 31 12:57:16 2020 No.12070358 >>12070343A singularity is broadly defined where a function isn't defined, this means that it approaches infinity or becomes degenerate. As for your question, are you dealing with real or complex valued functions?
 >> Anonymous Mon Aug 31 12:59:38 2020 No.12070366 >>12069611Last I've heard, you need an IQ of at least 130 to be able to join Mensa. That would be around the top 2%, although that is actually a lot more feasible than it sounds.However, it is more of a circle-jerk than anything, full of unironic autists and other mentals that cannot socialize with anyone. There are few benefits. If you think you can get 130 and work white-collar though, it can potentially impress prospective employers.t. Know a few people in Mensa, who aren't especially bright
 >> Anonymous Mon Aug 31 12:59:43 2020 No.12070367 >>12069611MENSA is very not worth it
 >> Anonymous Mon Aug 31 13:00:43 2020 No.12070371 >>12070366It's better to be an unironic autist than an ironic autist.
 >> Anonymous Mon Aug 31 13:00:58 2020 No.12070372 >>12069639Think of what the first dimension is, a straight line. Movement in a single direction.Now, think of the second dimension. Movement in two axes. Again, try the third dimension, movement in space. Notice how each time we move from one dimension to a higher one, we're adding a plane.Does time make sense as a dimension? Look up "tesseract" and try to understand what it is.
 >> Anonymous Mon Aug 31 13:03:10 2020 No.12070378 >>12070358The function I have is $g(z)=\frac{3}{z^2(z^2-z)}$. Here, I believe $z$ can be set equal to $x+iy$, which would make this a complex function.
 >> Anonymous Mon Aug 31 13:03:49 2020 No.12070380 >>12070371absolutely incorrect
 >> Anonymous Mon Aug 31 13:05:01 2020 No.12070387 >>12070378not who you responded to but it seems like you're trying to understand a property of complex-valued functions without really understanding what you're doing.I recommend going through a complex analysis book, because singularities will definitely be covered and they'll be covered at a time where you actually know what you're doing.
 >> Anonymous Mon Aug 31 13:06:22 2020 No.12070393 >>12070354>>12070288I'm really still at a loss on how to solve or even properly start question 19is the cross of a cosntant vector and a gradient function not 0? then the second resultant cross would also be 0? but its supposed to be -2a?
 >> Anonymous Mon Aug 31 13:07:37 2020 No.12070397 >>12070393>gradient functionmeant gradient vector
 >> Anonymous Mon Aug 31 13:08:07 2020 No.12070399 >>12070387The class I'm in right now has been doing complex functions for a while and I'm keeping up with the material. However, the professor has the habit of doing very simple examples and as such, it's confusing trying to apply what is shown to the problems that we're expected to solve. That being said, if you know of any good resources, I'd appreciate you telling me what they are.
 >> Anonymous Mon Aug 31 13:08:27 2020 No.12070402 >>12063261|x|/2 < 0 is nonsense. And epsilon isn't used.The first line just tells you that x_n is somewhere in the interval (x-epsilon, x+epsilon)
 >> Anonymous Mon Aug 31 13:10:56 2020 No.12070412 >>12070393come up with a representation for your constant vector, maybe (a1,a2,a3) to make it easier. you know what the vector representation of $\nabla$ is, so just actually carry out the cross product.the curl of a constant vector is 0, but you're not taking the curl since the order is reversed.
 >> Anonymous Mon Aug 31 13:11:36 2020 No.12070415 >>12070378The singularities in this case are where you would be dividing by zero, i.e. at z=0 and z=1. You have a pole of order 3 at z=0 and of order 1 at z=1.
 >> Anonymous Mon Aug 31 13:12:14 2020 No.12070419 >>12070399>any good resourcesunironically read the textbookfor your problem specifically, the singularities are points where the denominator would equal 0. so z^2=0 or z^2-z=0, and then solve for the possible values of z
 >> Anonymous Mon Aug 31 13:17:19 2020 No.12070438 >>12058471How do we determine the density of the interstellar medium?
 >> Anonymous Mon Aug 31 13:17:58 2020 No.12070443 >>12070415Thank you>>12070419I will take a look and see what the textbook says. Thank you for your help.
 >> Anonymous Mon Aug 31 13:30:23 2020 No.12070483 Is C isomorphic to R^2?
 >> Anonymous Mon Aug 31 13:48:29 2020 No.12070537 >>12070483Yes
 >> Anonymous Mon Aug 31 13:56:14 2020 No.12070562 >>12069234Could you clarify your question? I'm not sure what exactly you're asking.
 >> Anonymous Mon Aug 31 13:58:43 2020 No.12070574 >>12069234what?1=1^33+5=2^37+9+11=3^3
 >> Anonymous Mon Aug 31 14:19:32 2020 No.12070631 Math gained something when it defined the square root of -1 as imaginary numbers. Is there anything to be gained by assigning 1/0 as something similarly imaginary and seeing what you get?
 >> Anonymous Mon Aug 31 14:21:23 2020 No.12070635 >>12070631You can define anything in math, since it's axiomatic. The question isn't a matter of it but one of how useful defining something is. In most contexts, defining division by 0 leads to all sorts of contradictions and a system with contradictions isn't particularly useful. I'm going to assume you haven't taken CA, but there's something called the Riemann sphere where division by 0 is defined because it's well behaved.https://en.wikipedia.org/wiki/Riemann_sphere
 >> Anonymous Mon Aug 31 14:22:25 2020 No.12070639 >>12070635of if*
 >> Anonymous Mon Aug 31 14:23:25 2020 No.12070641 >>12070631no, and stop posting thisthe imaginary unit obeys the same rules of arithmetic and so it is able to be used alongside real numbers.if you try to define 1/0 as anything you get retarded shit that breaks the properties of multiplication and cannot be used. there are ways of defining it that are useful in very small subsets of things, but it's unlikely that this is what you're talking about.just read the (short) wikipedia page to get an idea why we don't do it: https://en.wikipedia.org/wiki/Division_by_zero
 >> Anonymous Mon Aug 31 15:10:50 2020 No.12070764 >>12070635Oh that is way cool! Thanks for this!>I'm going to assume you haven't taken CAYeah I don't even know what that means, I'm a geologist.
 >> Anonymous Mon Aug 31 15:15:51 2020 No.12070781 >>12070764Complex analysis, basically the study of complex valued functions.
 >> Anonymous Mon Aug 31 15:21:40 2020 No.12070794 >>12070781Wow, you high level math guys are nuts. Good stuff.
 >> Anonymous Mon Aug 31 15:25:45 2020 No.12070815 >>12070380He is correct, but that’s only because a convincing ironic autist is just a much more sick minded unironic autist coping with having a deformed brain.
 >> Anonymous Mon Aug 31 15:28:51 2020 No.12070822 >>12070631>Math gained something when it defined the square root of -1 as imaginary numbers. Is there anything to be gained by assigning 1/0 as something similarly imaginary and seeing what you get?Yes, https://en.wikipedia.org/wiki/Wheel_theory
 >> Anonymous Mon Aug 31 15:53:20 2020 No.12070921 >>12070631Yes, it's mainly used to study linear fractional transformations on the riemann sphere, it is essential to basically any higher study of conformal mappings. https://en.wikipedia.org/wiki/M%C3%B6bius_transformation#Poles_of_the_transformationThat being said it's really just notation to indicate the preimage of the North pole of the Riemann sphere, and it's only well defined in the context of a single linear fractional transformation.
 >> Anonymous Mon Aug 31 15:58:37 2020 No.12070948 >>12070822interesting, is there anything gained from this abstraction? I took grad level complex and we talked about mobius transforms all day but the professor never mentioned this structure.
 >> Anonymous Mon Aug 31 16:08:12 2020 No.12070983 >>12070366>t. Know a few people in Mensa, who aren't especially brightIsn't being bright a requirement for joining?
 >> Anonymous Mon Aug 31 16:08:49 2020 No.12070987 >>12070393if you are new to linalg / geometry, always ask yourself, what basis am I operating in? In this case the answer is simple, everything is an element of span $\{ \textbf{i}, \textbf{j}, \textbf{k} \}$. Express any vectors in this basis using generic constants $a_i$.
 >> Anonymous Mon Aug 31 16:09:49 2020 No.12070990 >>12070948Wheels are pretty useless structures because the entire point of having a 0 element in a field is to have an element that you can't divide by.
 >> Anonymous Mon Aug 31 16:13:58 2020 No.12071005 >>12070987>if you are new to linalg / geometrygeometry and actual lin alg are usually coordinate free...
 >> Anonymous Mon Aug 31 16:45:46 2020 No.12071142 File: 23 KB, 384x332, 1598702298347.jpg [View same] [iqdb] [saucenao] [google] [report] Does any else have an issue with their gay little babby hands getting sore/fatigued while taking notes with pen/pencil and paper? I don't remember this ever being an issue when I was a kid. How do I solve this problem?
 >> Anonymous Mon Aug 31 16:50:10 2020 No.12071160   In a new assignment they are teaching us binary, how to operate with them, logic gates and stuff, but I'm having trouble understanding decoders.I only understand that you give them n ammount of inputs, and you get 2^n ammount of outputsBut I don't understand how the 0 and 1 interact with each other on the table, or what's the use for themAAAAAAAA
 >> Anonymous Mon Aug 31 17:20:43 2020 No.12071247 >>12071142you shouldn't be writing everything down in class, add to what's already in the textbook.
 >> Anonymous Mon Aug 31 19:03:33 2020 No.12071596 File: 7 KB, 322x84, Capture.png [View same] [iqdb] [saucenao] [google] [report] how do I simplify this
 >> Anonymous Mon Aug 31 19:06:06 2020 No.12071605 >>12071596make a common denominator. multiply the left by $\frac{1+\text{cos}t}{1+\text{cos}t}$ and the right by that but with a minus
 >> Anonymous Mon Aug 31 19:08:00 2020 No.12071611 >>12071596Multiply numerator and denominator of left fraction by $1 + cost(t)$ and multiply numerator and denominator of right fraction by $1 - cost(t)$
 >> Anonymous Mon Aug 31 19:09:41 2020 No.12071626 File: 27 KB, 640x359, 626.jpg [View same] [iqdb] [saucenao] [google] [report] >>12071611*$cos(t)$, not $cost(t)$Oops
 >> Anonymous Mon Aug 31 19:13:16 2020 No.12071638 File: 58 KB, 1163x939, help.png [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Mon Aug 31 19:16:12 2020 No.12071651 >>12071638don't help him this much!
 >> Anonymous Mon Aug 31 19:25:21 2020 No.12071681 File: 674 KB, 671x1024, 1598804229749.png [View same] [iqdb] [saucenao] [google] [report] Are there any supplements I can take to help heal brain damage?
 >> Anonymous Mon Aug 31 19:26:00 2020 No.12071686 >>12071605>>12071611>>12071638Thanks all, I got a common denominator but made a retarded mistake
 >> Anonymous Mon Aug 31 19:26:27 2020 No.12071688 >>12071681no, brain damage is permanent
 >> Anonymous Mon Aug 31 19:27:49 2020 No.12071695 >>12071688Really?
 >> Anonymous Mon Aug 31 19:29:21 2020 No.12071697 >>12071695Depends, but mostly yes.
 >> Anonymous Mon Aug 31 19:29:26 2020 No.12071698 >>12071695if you're talking about damage to neurons then yes. the body cannot regenerate neurons. if you have inflammation from a concussion then that can heal.
 >> Anonymous Mon Aug 31 20:19:15 2020 No.12071821 File: 31 KB, 739x415, koma_chan.jpg [View same] [iqdb] [saucenao] [google] [report] Please someome help me I'm begging you, I need this done in less than an hour:A man is running with an acceleration of 3,6m/s^2 for 10/3s and then he keeps running with a constant velocity until he reaches the end of the road. The road's lenght is 100m.1)How long does it take for him to reach the end of the road? 2)He could go faster if his acceleration in the beginning was faster, thus reaching his maximum speed earlier. If his maximum speed is the same as in the first question, then what would be the required acceleration for him to run the 100m in 9,9s?
 >> Anonymous Mon Aug 31 20:23:07 2020 No.12071833   >>12071821does he start off still?distance traveled in the first 10/3s: $\frac{1}{2}at^2=\frac{1}{2}(3.6)(\frac{10}{3})^2$velocity after the first 10/3s: $v=at=3.6*\frac{10}{3}$total time to travel: $\frac{10}{3}+\frac{100-x}{v}$, where x and v are your answers to the first two things (distance traveled in first 10/3s and velocity at the end of acceleration)
 >> Anonymous Mon Aug 31 20:24:48 2020 No.12071838 >>12071833not sure why my second one failed, maybe because of the commatotal time to travel: $\frac{10}{3}+\frac{100-x}{v}$
 >> Anonymous Mon Aug 31 20:27:01 2020 No.12071843 >>12071821just trying again not sure why it keeps breakingdoes he start off stationary?distance traveled in the first 10/3s: $1/2at^2=1/2(3.6)(10/3)^2$velocity after the first 10/3s: $v=at=3.6∗10/3$total time to travel: $\frac{10}{3}+\frac{100-x}{v}$ , where x and v are your answers to the first two things (distance traveled in first 10/3s and velocity at the end of acceleration)
 >> Anonymous Mon Aug 31 20:28:03 2020 No.12071846 >>12071843okay what the fuck. it's working in the practice window
 >> Anonymous Mon Aug 31 20:30:40 2020 No.12071848 >>12071843Yes, stationary.I didn't have a problem in the first question, the distance traveled during acceleration I found to be 20m while his maximum speed was 12m/s and the total time for the 100m road I'm not sure if it's 10s or 13,333s.But my real difficult is in question 2, I feel like I don't have enough info to answer it.Thank you for the fast answer though.
 >> Anonymous Mon Aug 31 20:33:59 2020 No.12071854 >>12071848Is this calculus based physics?
 >> Anonymous Mon Aug 31 20:34:58 2020 No.12071859 >>12071854It's just basic physics, I don't think calculus is even needed here
 >> Anonymous Mon Aug 31 20:37:16 2020 No.12071866 >>120718212nd question:$100=\frac{1}{2}at_1^2+vt_2$t1+t2=9.9s, v is the velocity you get from the last partyou also have $\frac{1}{2}at_1^2=\frac{v}{2}t_1$ from the distance traveled in the accelerating period. $a=\frac{v}{t_1}$plug this back in: $100m=vt_1+vt_2=v(t_1+t_2)$you know v and you know t1+t2=9.9shope typesetting fucking works this time
 >> Anonymous Mon Aug 31 20:40:32 2020 No.12071871 >>12071866can someone tell me WHY the fuck this is working in the test window but not when I send the postif this isn't coherent enough just let me know and I'll make it work. I also did something wrong, so here's the punchline:$100m=vt_1+v(9.9-t_1)$solve for t1 and then you plug back into the expression for a to get the acceleration
 >> Anonymous Mon Aug 31 20:44:17 2020 No.12071880 >>12071843>>12071866I think the first bracket of your [/math] is getting absorbed by the preceding exponent/subscript.
 >> Anonymous Mon Aug 31 20:46:03 2020 No.12071884 >>12071880it looked fine in the test window. I think it has to be a bug
 >> Anonymous Mon Aug 31 20:51:54 2020 No.12071897 >>12071866Thanks, but where does the 1/2at^2=v/2t1 comes from?
 >> Anonymous Mon Aug 31 20:55:03 2020 No.12071901 >>12071897assuming constant acceleration (which I think is fair), distance traveled over a period of acceleration is equal to $\frac{1}{2}at^2+v_i t=\frac{v_f+v_i}{2}t$, where vf is the final velocity after acceleration and vi is the initial velocity. In your case, vi=0
 >> Anonymous Mon Aug 31 21:12:14 2020 No.12071941 File: 950 KB, 1198x677, Comfy pepe.png [View same] [iqdb] [saucenao] [google] [report] I just want to thank all the people who take time out of their day to help us brainlets. You guys go above and beyond.
 >> Anonymous Mon Aug 31 21:44:56 2020 No.12072016 >>12071941I just graduated and I like answering analysis questions to stay fresh, it was hard for us the first time around too.
 >> Anonymous Mon Aug 31 22:09:03 2020 No.12072060 >>12072016Did you cover Lebesgue integration/measures in your Analysis II class? I only ask because the answer seems to vary depending on who I talk to.
 >> Anonymous Mon Aug 31 22:32:31 2020 No.12072096 >>12072060yes, math 105 with based Pugh at Berkeley. The first third covers multivariable analysis, the rest is on Lebesgue integration. Then I saw measure theory again but in more generality in the intro grad analysis class.
 >> Anonymous Mon Aug 31 22:47:47 2020 No.12072132 So I'm trying to take the integral of u^(1/2) but I keep getting (3/2)u^(3/2), is that not how it's supposed to be? wolframalpha keeps on telling me its (2/3)u^(3/2)
 >> Anonymous Mon Aug 31 22:49:55 2020 No.12072141 >>12072132$\int x^n dx = \frac{1}{n+1} x^{n+1} + c$
 >> Anonymous Mon Aug 31 22:51:08 2020 No.12072145 >>12072141Fuck. I got it, thank you.
 >> Anonymous Mon Aug 31 22:53:25 2020 No.12072150 >>12063213>Are Integrals the inverse of Derivativesyes, basically. >how difficultOne of the most challenging parts of calculus is integrals. But it's such a broad topic you spend three classes (calc 1, calc 2, and calc 3) going over them in different ways. Personally I felt calc 3 was the hardest. But since you're just starting out it shouldn't be too hard, just some tricky substitution stuff. You need to be very good at algebra to do u-substitution (what you're going to do) integrals quickly. >>12063742t0 is by definition 0, as that's what the 0 means (at least the vast majority of the time)>>12066568different forms of the solid not found in the "solid" region. The forms differ in microstructures and are reliant on the temperature. >>12068897Nitrogen is very electronegative and carbon chains are very not electronegative. Because of this, proline is more polar.>>12069411Humans are the only species intelligent enough to have the foresight to think about such abstract things as "extinction." No other species cares about nor can comprehend the idea.
 >> Anonymous Mon Aug 31 22:54:37 2020 No.12072153 >>12072150>t0 is by definition 0, as that's what the 0 means (at least the vast majority of the time)everything is mostly right except this. t0 is "initial time" which is sometimes taken to be 0.
 >> Anonymous Mon Aug 31 22:57:47 2020 No.12072158 >>12072096That's awesome. Dr. Pugh's book is actually what I used for my Analysis I class. Does he still have his long hair?
 >> Anonymous Mon Aug 31 23:20:42 2020 No.12072199 >>12072158Yes lmao, he also wore suspenders and used to have a car with the license plate "DIFFEO".
 >> Anonymous Mon Aug 31 23:23:27 2020 No.12072203 >>12072199Based.
 >> Anonymous Tue Sep 1 00:12:20 2020 No.12072280 File: 77 KB, 1908x398, Screen Shot 2020-08-31 at 10.59.57 PM.png [View same] [iqdb] [saucenao] [google] [report] I just want to make sure I'm doing these right, but this would 2, right?
 >> Anonymous Tue Sep 1 00:15:57 2020 No.12072292 File: 26 KB, 615x194, phys.png [View same] [iqdb] [saucenao] [google] [report] Yeah I'm thinking I might be fucking retardedThe answer is 810N (2 s.f.)I have it set up where my opposite side (Ty) for two vector triangles is 70*9.81 = 686.7NSo to find Tx I've done 686.7/tan(25) = 1473NNow sqrt(686.7^2)+(1473^2) = 1625 for the hypotenuse THow the FUCK am I meant to reach 810N for the tension from this? The explanation for the answer feels esoteric.
 >> Anonymous Tue Sep 1 00:17:54 2020 No.12072299 >>12072292divide by 2"each side of the rope"
 >> Anonymous Tue Sep 1 00:19:07 2020 No.12072300 >>12072299I divided by 2 a while ago and found 810 that way but I wasn't sure why that worked. God the wording on these questions fucks me over sometimes, thanks for the quick reply.
 >> Anonymous Tue Sep 1 00:23:21 2020 No.12072311 >>12072292Each section of rope holds part of the weight. Due to symmetry it is half. Also, use sin(theta) instead of tan and hypot, less error propagation and room for mistakes.
 >> Anonymous Tue Sep 1 00:26:59 2020 No.12072318 >>12072280yes, by demorgan's laws.
 >> Anonymous Tue Sep 1 00:30:49 2020 No.12072324 >>12072311So if I work out symmetrical tightrope questions in the future with two right angled triangles like that then just halve the result it'll always make sense? It gave me the answer, but for some reason I can't see why it's logical to do that. I had two hypotenuse sides of 1625 converging to the same point down the 686.7 weight, and that's confusing me.Also could you give me a numerical example of using sin to find adjacent when I only have the angle and opposite side?
 >> Anonymous Tue Sep 1 00:32:19 2020 No.12072327 >>12072318Thanks.
 >> Anonymous Tue Sep 1 00:33:45 2020 No.12072331 >>12072324they specifically asked "each side" meaning that the answer you got, which counters out the total force due to the man, must be divided by two since both sides are contributing the vertical force.for the other point he's being an idiot, tangent relates the two legs of a right triangle given the angle. not sin or cos
 >> Anonymous Tue Sep 1 00:39:19 2020 No.12072342 >>12072331>since both sides are contributing the vertical force.Ah, that made it make sense now. Thanks again, and sorry if these questions are extra retarded for this place's standards.
 >> Anonymous Tue Sep 1 00:40:03 2020 No.12072344 >>12072342there are worse questions
 >> Anonymous Tue Sep 1 00:41:23 2020 No.12072348 >>12072344I'm a dropout with zero math knowledge and this is my third week, hopefully I can ride with you guys in a year or two.
 >> Anonymous Tue Sep 1 00:41:26 2020 No.12072349 >>12072344Are there, though?
 >> Anonymous Tue Sep 1 00:46:47 2020 No.12072354 >>12072349I would say these are all worse or asked in a worse way:>>12061133>>12063372>>12063742>>12063832>>12064131>>12065730>>12069411>>12069639>>12070631>>12071681
 >> Anonymous Tue Sep 1 00:48:39 2020 No.12072358 >>12063447books? not quite, just a bunch of papers. any books will mostly be on atomic physics because there's very little that's specific to atomic clocksdo you have any questions?
 >> Anonymous Tue Sep 1 00:49:36 2020 No.12072360 >>12072354Fair enough.
 >> Anonymous Tue Sep 1 00:51:28 2020 No.12072365 >>12072348Here's a fun fact for you: The rationals have a Lebesgue measure of 0. This means that if you pick a real number at random, there's basically a 0% chance that you'll pick a rational number.
 >> Anonymous Tue Sep 1 00:51:57 2020 No.12072367 >>12070574>>12070562Oh I see, thanks!I was thinking1 = 1^21+3 = 2^21+3+5 = 3^21+3+5+7 = 4^2
 >> Anonymous Tue Sep 1 00:52:29 2020 No.12072368 File: 20 KB, 575x323, brain.jpg [View same] [iqdb] [saucenao] [google] [report] >>12072365Ah yes, I understand now.
 >> Anonymous Tue Sep 1 00:54:48 2020 No.12072373 >>12072365I wish I could watch you reeling on the ground choking on your own blood and vomit from a punctured lung, reddit faggot
 >> Anonymous Tue Sep 1 00:55:35 2020 No.12072374 >>12072368Almost every single number is not expressible in the form of $\frac{a}{b}$, where $a,b$ and $b \neq 0$ are whole numbers.
 >> Anonymous Tue Sep 1 00:57:17 2020 No.12072376 >>12072374I have no idea what that means man.
 >> Anonymous Tue Sep 1 00:58:36 2020 No.12072377 >>12072376he's just being autisticpractically 0% of the numbers can be written as a fraction. because for every one that can, there are so so so many that can't
 >> Anonymous Tue Sep 1 01:01:26 2020 No.12072382 >>12072365I also like the fact that degenerate (det 0) matrices have measure 0. So when solving linear ODE systems you can always assume your system is non degenerate lmao.
 >> Anonymous Tue Sep 1 01:30:03 2020 No.12072432 >>12072382if you were a matrix you'd have determinant 0 :)
 >> Anonymous Tue Sep 1 01:36:01 2020 No.12072445 >>12072432You mean I'd be singular?
 >> Anonymous Tue Sep 1 01:38:30 2020 No.12072452 >>12072432lmao if I ever TA linalg to freshmen I will make sure to call out degeneracy wherever I see it.
 >> Anonymous Tue Sep 1 07:45:39 2020 No.12073146 >>12072365Meanwhile in real life there is like a 0% chance he picks he picks an irrational number that isn't pi or e.
 >> Anonymous Tue Sep 1 08:32:26 2020 No.12073308 >>12058471Hey, what the fuck happened with these thread, there used to be a lot of useful links in the OP, but now it's all lazily created. What the fuck happened with tohou poster? And why the fuck aren't people putting a little effort in the OP anymore? We're the science board, but we act like the retard board
 >> Anonymous Tue Sep 1 08:39:29 2020 No.12073323 How do I break a number down into smaller multiples?Like 27 is 3x3x3 obviously cube root, but say 100, it can be 2x2x5x5, or 4x5x5, 36 can be 3x3x4 or 4x9 etcAnd if I have a prime number, or set a limit on the biggest multiple I can use and cant find a solution, how do I find the closet smaller number that has a solution?Like say say if I have 99 I could use 3x3x11, but if I set the max number to 9, then I dont have a solution, and can drop down to 98 and use 2x7x7
 >> Anonymous Tue Sep 1 10:51:45 2020 No.12073628 >>12073308>What the fuck happened with tohou poster?God I miss the touhou poster, what happened to them
 >> Anonymous Tue Sep 1 10:59:39 2020 No.12073648 File: 175 KB, 800x741, 1598972373459.png [View same] [iqdb] [saucenao] [google] [report] I finished my bachelor degree at the age of 25 today.How late am I?
 >> Anonymous Tue Sep 1 11:01:41 2020 No.12073655   >>9371155Not an argument
 >> Anonymous Tue Sep 1 11:04:59 2020 No.12073661 >>12073648grats, I'll probably finish by 24
 >> Anonymous Tue Sep 1 11:06:03 2020 No.12073663 >>12073661Yes but how late am I?
 >> Anonymous Tue Sep 1 11:06:35 2020 No.12073664 >>12073663Bachelors is 4 yes? Assuming that most students go straight into college after HS, they'll get their bachelors at 22. So 3 years late.
 >> Anonymous Tue Sep 1 11:13:58 2020 No.12073680 >>12073664How damaging is that when you're looking for jobs?
 >> Anonymous Tue Sep 1 11:14:45 2020 No.12073682 >>12073680Depends on the employer, most would just ask why you took so long so have an proper excuse.
 >> Anonymous Tue Sep 1 11:25:46 2020 No.12073708 >>12073682I switched degrees basically so how bad is that?
 >> Anonymous Tue Sep 1 11:26:30 2020 No.12073709 >>12073708Just tell them that you swapped then, that is a perfectly valid reason.
 >> Anonymous Tue Sep 1 11:27:06 2020 No.12073711 >>12073709But the facts still look bad don't they?
 >> Anonymous Tue Sep 1 11:49:24 2020 No.12073752 File: 137 KB, 997x238, 2A1335C2-ED92-43FE-B97F-8C9B20AC6E96.jpg [View same] [iqdb] [saucenao] [google] [report] I’m having a hard time understanding this problem. I know the answer is the harmonic mean but I don’t know why. 1/a is the rate at which the first half is filled and 1/b is the rate at which the second is filled. So shouldn’t 1/a+1/b be the rate at which the whole pool is filled per hour? According to the internet 1/a+1/b is the rate at which half a pool is filled per hour when the pool is not divided.
 >> Anonymous Tue Sep 1 12:46:28 2020 No.12073893 >>12073752The first half is filled at 1/a. The other half is filled at 1/b. If you put both pipes into the same half, its 1/a+1/b. Since the pool volume doubled, you need to double it.
 >> Anonymous Tue Sep 1 12:48:46 2020 No.12073898 >>12073893Yeah I think I get it now thanks
 >> Anonymous Tue Sep 1 12:51:56 2020 No.12073907 File: 89 KB, 322x500, How to prove it.png [View same] [iqdb] [saucenao] [google] [report] I'm too dumb/lack the foundations to work through pic related, could someone recommend a book that will teach me the skills I need? I'm not even sure what to look for, basic algebra?
 >> Anonymous Tue Sep 1 13:22:12 2020 No.12073973 why people who like nuclear are so vile and easily offended?why does it look basically like a cult?
 >> Anonymous Tue Sep 1 13:52:05 2020 No.12074046 >>12073907If you can't work through that book, then all I can do is recommend a different book in that same subject. There really should be no prerequisites for that book.
 >> Anonymous Tue Sep 1 13:55:37 2020 No.12074057 >>12073146$\sqrt{2}$ nigger, it's a classic proof
 >> Anonymous Tue Sep 1 14:05:38 2020 No.12074100 >>12073323what?the most useful way of breaking down a number into its multiples is to use its "prime factorization," meaning you break it down into prime numbers.this is useful because every number has a unique prime factorization. so if you're doing 100, you only have 2x2x5x5, since 4x5x5 you can break the 4 into 2x2
 >> Anonymous Tue Sep 1 14:38:35 2020 No.12074207 >>12074057Even better:$\sqrt{p}$ where $p$ is a prime.
 >> Anonymous Tue Sep 1 15:16:22 2020 No.12074294 >>12074207based, I didn't remember this little factoid, very elegant example.
 >> Anonymous Tue Sep 1 15:35:40 2020 No.12074339 >>12074294Nothing to do with number theory is elegant.
 >> Anonymous Tue Sep 1 15:48:03 2020 No.12074382 >>12074339Explain this, then.https://en.wikipedia.org/wiki/Euclid%27s_theorem
 >> Anonymous Tue Sep 1 17:06:47 2020 No.12074688 File: 10 KB, 165x306, images.jpg [View same] [iqdb] [saucenao] [google] [report] Have any of you girls ever used this uridine stuff?
 >> Anonymous Tue Sep 1 17:32:16 2020 No.12074776 >>12074688just drink coffee
 >> Anonymous Tue Sep 1 17:36:20 2020 No.12074789 >>12074776But coffee doesn't do the same thing.
 >> Anonymous Tue Sep 1 17:40:23 2020 No.12074800 >>12074789you don't need supplements other than maybe vitamin D, just eat a varied diet of fresh foods and local meats and fish. It's not even that much more expensive than eating junk food if you stick to buying basic unprocessed greens and protein.
 >> Anonymous Tue Sep 1 20:50:02 2020 No.12075300 in a euclidean space, if i have an open set U and a closed ball B that's strictly contained in U, is it always possible to define an open ball within U that also contains C? it seems to me like it should be the case but I don't know how to prove it, the radius of the supposed open ball messes me up
 >> Anonymous Tue Sep 1 20:56:36 2020 No.12075317 >>12075300I’m too tired to think about it but here:http://mathonline.wikidot.com/closed-unit-ball-criterion-for-finite-dimensional-normed-linIntuitively the answer is yes.
 >> Anonymous Tue Sep 1 21:09:31 2020 No.12075349 >>12075317Get some sleep, anon.
 >> Anonymous Tue Sep 1 21:29:18 2020 No.12075391 >>12075317thanks, i'll check it out, although i think i got an idea shortly after posting:consider the boundaries of U and B, and assume their distance is 0. since the boundary of U is closed and the boundary of B is compact then their intersection should be non empty. and also, $B \subset U$, so that intersection is contained in U. thus, U contains a point of its boundary, and can't be open which would be a contradictionand if the distance of the boundaries is k>0, then B would be contained in an open ball with its same radius +kdoes that look good enough?
 >> Anonymous Wed Sep 2 00:59:54 2020 No.12075893 >>12058471Need help with this.for any matrix $T$, given that $||T|| < 1$ for any matrix norm, prove that the succession $\{x_k\}_{k=0}^{\infty}$ given by $x_k = Tx_{k-1} + c$ ($c$ a fixed vector in $\mathbb{R}^n$ ) converges for any vector $x_0 \in \mathbb{R}^n$ to a vector $x \in \mathbb{R}^n$ that satisfies the equation $x = Tx + x$
 >> Anonymous Wed Sep 2 01:02:54 2020 No.12075901 >>12075893shit meant $x = Tx + c$
 >> Anonymous Wed Sep 2 01:33:48 2020 No.12075947 >>12075300Yes, this idea of sandwiching sets in between other sets features heavily in an intro grad topology and analysis class. It depends a lot on the separation axioms of your topological space: if you have a metric (eg. Euclidean distance) then you are automatically operating in a nice T4 Normal space where you have a ton of space to work in.https://en.wikipedia.org/wiki/Normal_spaceAssuming B is a proper subset of U, it is closed and bounded so B is compact. Come up with a way of expressing an infinite open cover of B which is contained in U, from that you obtain some finite cover which you can union to get your desired open set.
 >> Anonymous Wed Sep 2 01:46:44 2020 No.12075967 >>12075893fun question, what class is it for? I found this nice overview of the topic: https://www-users.math.umn.edu/~olver/num_/lni.pdf
 >> Anonymous Wed Sep 2 01:50:37 2020 No.12075972 File: 4 KB, 159x78, file.png [View same] [iqdb] [saucenao] [google] [report] Is there a difference between these two wave equations? I assume since they're homogeneous I can make the unit vector whatever I want.
 >> Anonymous Wed Sep 2 01:55:34 2020 No.12075980 >>12075972Assuming B_x is constant then this is just a stupid of way of expressing what should be said in words: x^hat and z^hat both solve the wave equation in one dimension.
 >> Anonymous Wed Sep 2 02:00:46 2020 No.12075989 >>12075967numerical analysis
 >> Anonymous Wed Sep 2 02:03:40 2020 No.12075996 >>12075980Meaning that the unit vector attached to the wave equation has no bearing on the direction of the solution?
 >> Anonymous Wed Sep 2 02:07:34 2020 No.12076005 >>12075989>>12075967thanks, thats a great resource there, btw the proof relies on the fact that $\rho(A) = \inf \{||A||\}$ so just proving that is fine.now I have the problem of proving the error bounds:[eqn]||x - x_k|| \leq ||T||^k ||x_0 - x|| \\ ||x - x_k|| \leq \frac{||T||^k}{1 - ||T||} ||x_1 - x_0||[/eqn]
 >> Anonymous Wed Sep 2 02:11:36 2020 No.12076009 >>12075996dude notation varies so much in PDE, you're gonna have to give us some context. What space are you operating in, what class of solutions are you dealing with, what the fuck is B_x etc.
 >> Anonymous Wed Sep 2 02:14:23 2020 No.12076012 >>12076009It's the wave equation for EM radiation in free space. B_x is the amplitude of the x component of the field, B_y and B_z are zero so the field is purely oscillating in the x direction
 >> Anonymous Wed Sep 2 02:37:52 2020 No.12076037 >>12075972I can't fucking read this. I know physics though.Does that say $B_z \hat{z} \text{ or } B_x \hat{z}$ for the top line?
 >> Anonymous Wed Sep 2 02:37:58 2020 No.12076039 if space is so big then why am i so dense?
 >> Anonymous Wed Sep 2 02:38:36 2020 No.12076040 >>12076012oh I guess it's standard notation in EM, I only took a pure math class on PDE. In any case, you are right that they are the same wave operator $\Box u(y,t) = 0$ where $c^2 = \mu \epsilon$. In the grad class that I took we would set any constants like B_x to 1 without loss of generality, they have no effect on the operator, it's really defined by the light speed cone/propagation speed $\sqrt{\mu \epsilon\}$.
 >> Anonymous Wed Sep 2 02:40:33 2020 No.12076041 >>12076039because you are a Kolmogorov space.
 >> Anonymous Wed Sep 2 02:47:30 2020 No.12076044 >>12076005always remember the old trick [eqn] ||x_0-x_k|| = ||x_0-x + x - x_k|| \leq ||x_0-x|| + ||x-x_k|| [/eqn]
 >> Anonymous Wed Sep 2 03:01:34 2020 No.12076056 >>12076041i dont speak russian sorry
 >> Anonymous Wed Sep 2 03:06:10 2020 No.12076070 >>12076056you practically have to learn russian to pass a topology & measure theory class.
 >> Anonymous Wed Sep 2 03:10:32 2020 No.12076082 >>12076070whats topology? google gave me a bunch of weird symbols when i searched
 >> Anonymous Wed Sep 2 03:39:49 2020 No.12076131 Strictly speaking topology isn't about coffee mugs and tori, it's the study of continuous functions. In a real analysis class you will use the idea of distance by defining a metric and spamming epislon-deltas to formalize everything you use in calculus: open/closed sets, continuous functions, convergence of sequences and series etc. It turns out that the most important definitions can be expressed simply using open sets, rather than epsilon-delta definitions. So if you give me any space, and then define for me which sets I should deem to be "open", I can define what a continuous function or a compact set looks like in your space. The topology is that collection of sets that we will consider to count as open. Basically you can define continuity on extremely exotic spaces without needing to create a metric. Of course any normed vector space induces a metric $d(x,y) = |x-y|$, which then induces the standard topology: we define a set to be open if it is a countable union of open balls $B_\epsilon (x_0) = \{ x: d(x,x_0) < \epsilon \}$. So every normed vector space is a metric space, and in turn is a topological space.
 >> Anonymous Wed Sep 2 03:41:46 2020 No.12076134 File: 102 KB, 1360x424, Screen Shot 2020-09-02 at 12.28.26 AM.png [View same] [iqdb] [saucenao] [google] [report] >>12076082sorry, here's your (you)
 >> Anonymous Wed Sep 2 03:54:34 2020 No.12076158 >>12076131>>12076134i really hope that whoever is paying you to know and use this shit is paying you well, cus to me its all gibberishand i tried to learn computer engineering
 >> Anonymous Wed Sep 2 04:30:34 2020 No.12076207 Is it true that nofap is a jewish scheme to make me gay? I get gay thoughts when I start nofapping but they disappear when I fap to straight stuff.
 >> Anonymous Wed Sep 2 05:10:05 2020 No.12076276 File: 44 KB, 1082x655, how.png [View same] [iqdb] [saucenao] [google] [report] Hello, king of brainlets here.How can plugging the first equation into the second yield the third? thank you
 >> Anonymous Wed Sep 2 09:58:15 2020 No.12076771 >>12058471How can I solve this:$x^2y''-3xy'+3y=2x^2, \,\,\,1  >> Anonymous Wed Sep 2 10:05:55 2020 No.12076792 >>12076771P.s. the eigenvalues I found are [math] 1+( \frac{n \pi}{ \ln2} )^2$and the eigen functions are $x^2 \sin( \frac{n \pi}{ \ln2} \lnx)$
 >> Anonymous Wed Sep 2 11:13:43 2020 No.12076934 >>12076037B_x zhat
 >> Anonymous Wed Sep 2 11:17:52 2020 No.12076942 >>12076276There are roughly 9 undefined symbols in that image. Unless someone can read minds through the internet, or happens to know exactly what this material, I don't think anyone can help you without more context.
 >> Anonymous Wed Sep 2 12:16:32 2020 No.12077104 how many holes does a straw have?
 >> Anonymous Wed Sep 2 12:17:49 2020 No.12077112 when they say, "the laws of physics are the same for non-accelerating observers," are accelerating frames of reference the entire point of general relativity?
 >> Anonymous Wed Sep 2 12:18:47 2020 No.12077118 >>12076771>>12076792nvm I got it now. In case you are interested it's not in self-adjoint form and while I had found the weight function $( \frac{1}{x^5} )$, I was trying to calculate the coefficients using the term $2x^2$ instead of the one multiplied with the weight function that brings it into self-adjoint form (sturm-liouville equation). Self-adjoint form is extreme autism.
 >> Anonymous Wed Sep 2 12:26:24 2020 No.12077144 >>12077112special relativity covers ityou only need general when you care about gravity
 >> Anonymous Wed Sep 2 13:00:11 2020 No.12077254 Bros, how is partial x/partial v of ln(u*cosv) = -tanv?I'm looking at the wolfram alpha solution of it but I'm getting confused by it.
 >> Anonymous Wed Sep 2 13:13:39 2020 No.12077301 >>12077254Am I getting trolled here? There's no x in that equation, so any partial with respect to it would be 0.
 >> Anonymous Wed Sep 2 13:14:19 2020 No.12077303 >>12077301I forgot to write x = ln(u*cosv) sorry
 >> Anonymous Wed Sep 2 13:18:52 2020 No.12077321
 >> Anonymous Wed Sep 2 13:31:28 2020 No.12077377 >>12077254Derivative of $\ln(x)$ is $\frac{x'}{x}$. So derivative wrt $v$ of $\ln(u\cos v)$ is $\frac{1}{u\cos v}\times \frac{\partial}{\partial v}(u\cos v)$. Now what is $\frac{\partial}{\partial v}(u\cos v)$?
 >> Anonymous Wed Sep 2 13:36:52 2020 No.12077397 >>12077377Oh okay yeah, it becomes -usinv and then -usinv/ucosv becomes -tanv, thank you!
 >> Anonymous Wed Sep 2 13:52:21 2020 No.12077441 >>12077144this is not correctspecial relativity does not account for accelerating frames. you just use non-inertial classical mechanics
 >> Anonymous Wed Sep 2 14:35:19 2020 No.12077574 hardcover or paperback for math books?
 >> Anonymous Wed Sep 2 14:35:44 2020 No.12077576 >>12077104a straw is a cylinder, which isn't a smooth surface. It doesn't make sense to count holes.https://en.wikipedia.org/wiki/Surface_(topology)#Closed_surfaces
 >> Anonymous Wed Sep 2 14:38:36 2020 No.12077587 File: 157 KB, 759x646, 123.png [View same] [iqdb] [saucenao] [google] [report] Hey bros, what do I need to know in order to start learning about Electric Charges (Chapter 21)? My professor assumed that everyone knows about Coulombs, Electric Fields, Ohms, etc despite us only having taken Physics 1 so I went straight to the textbook and I noticed that we'll only learn about what he's talking about in a month in Physics 2.Do I need to know about Kinetic Theory of Gasses, The Second Law of Thermodynamics, and Entropy to get started on Electric Charges? Attached is the ToC of the textbook.
 >> Anonymous Wed Sep 2 14:40:57 2020 No.12077589 >>12077587>Do I need to know about Kinetic Theory of Gasses, The Second Law of Thermodynamics, and Entropy to get started on Electric Charges?absolutely not. these topics are entirely unrelated to what you'll be doing.electricity is largely self-contained. these chapters should be teaching you the subjects you mentioned in your first line.
 >> Anonymous Wed Sep 2 14:44:45 2020 No.12077600 >>12077589>absolutely not. these topics are entirely unrelated to what you'll be doing.>electricity is largely self-contained. these chapters should be teaching you the subjects you mentioned in your first line.Thank you so much anon, my electrical circuit professor hit us with this out of the left field and kept on questioning how we didn't learn this when we learned Physics 1 (Chapters 1-15). We only talked about Power and that's about it so no one in the class has any idea about what he's talking about.
 >> Anonymous Wed Sep 2 14:45:44 2020 No.12077603 >>12073711stop worrying most jobs dont worry about age just skill, just turn switching majors into a positive like you have a better perspective of something