# Calculus

- Elementary functions. Calculating limits, derivatives and integrals. Optimization problems
 Views: 134 Announcement: PF Member Award voting is open! Dec12-13 Meta Thread / Thread Starter Last Post Replies Views Please post any and all homework or other textbook-style problems in one of the Homework & Coursework Questions... Feb23-13 10:24 AM micromass 1 37,644 Hello! We know how is a primitive of a any function (file 1), but how will be the graphic of a function like the at... T 04:03 PM Jhenrique 0 61 OK, I'm new to multi-variable calculus and I got this question in my exercises that asks me to integrate e^{-2(x+y)} ... T 02:30 PM Shyan 3 132 Hellow!! If we can equal the first derivative with a trigonometric function: \frac{dy}{dx}=tan(\theta) So, the... T 01:29 PM Jhenrique 13 272 ## \int^{\infty}_{-\infty}dxe^{-ax^2}=\sqrt{\frac{\pi}{a}}## Is it correct also when ##a## is complex? T 08:28 AM voko 2 154 I'd like to know what is a integral valued in one point (F(c)) and what is derivative valued in one interval... T 06:48 AM Jhenrique 0 154 I this old thread it mentions that the indefinite integral of f'(x)/f(x) is log(|f(x)|)+C which means that there is... Y 05:10 PM Mark44 30 679 How can I find the limit in question 7e and 7g? Finding limits is difficult!:cry: Y 07:21 AM haha1234 2 192 I am a graduate student and during my research I have come across this integration formula shows in attached image... Y 07:14 AM hash054 9 426 I believed the definitions of derivative that we know was really definitions f'(x_0)=\lim_{x\rightarrow... Y 05:34 AM Jhenrique 6 303 Hi, I figured out the only redundancy to my problem is this: I'll start off with a simple case, where w1,w2 are... Y 02:59 AM c0der 2 269 pi ∫sin^2(nx)/sin^2(x) dx 0 I tried using mathematical induction and did arrive at the correct result... Dec11-13 03:18 PM Mandelbroth 3 348 I’m having a little trouble understanding why Green’s Theorem is defined as; ∮_C P dx+Q dy = ∬_D dA Instead of;... Dec11-13 05:09 AM TysonM8 2 270 How do I integrate: \int\dfrac{dx}{(a^2sin^2(x)+b^2cos^2(x))^2} Multiplying and dividing by sec^4(x) doesn't work,... Dec10-13 08:48 PM Simon Bridge 4 237 I am confused with solving for horizontal asymptotes. I know you are supposed to find limits to positive and negative... Dec10-13 07:01 PM genevievelily 3 177 Simple question; http://i.imgur.com/gGj1NsO.jpg?2 Why isn't it \sum am (from m=1 to infinity) Thanks in... Dec10-13 12:58 PM jbunniii 1 205 does e^-x*x^(t-1)= e^(t*ln(x)-ln(x)-x) heres my reasoning: x=e^ln(x) e^-x*x^(t-1)= e^-x*e^(ln(x)(t-1))=... Dec10-13 12:21 PM HallsofIvy 3 268 I remember when I took Calculus B in college. I had never learned any math by reverse engineering before, but when I... Dec10-13 11:44 AM HallsofIvy 1 163 Given f(x(t), y(t)), I know that ∂f/∂x and ∂f/∂y is true (with ∂) because, by definition, use ∂ where f is function of... Dec10-13 10:47 AM Mark44 1 239 I have some questions, all associated. So, first, if a curve level is defined as: f(x,y)=k or vectorially as:... Dec10-13 08:01 AM Jhenrique 1 396 \displaystyle\int_0^\pi\dfrac{x dx}{a^2sin^2(x)+b^2cos^2(x)} I have to prove this to be equal to \dfrac{\pi^2}{2ab}... Dec10-13 07:56 AM D H 1 175 y =f(x), and y'=df(x)/dx, F(y)=y^3+(y')^2 how to deal with the (y')^2 when i calculate dF(y)/dy? thanks. Dec9-13 02:48 PM HallsofIvy 4 355 Does ##g(x,y,z)## (the equation of the surface) need positive z or negative z when doing a surface integral? ... Dec9-13 02:46 PM HallsofIvy 2 283 Hey, does anyone know of a proof that the sinc function Si(x) = \int \frac{\sin x}{x} \, dx is not elementary?... Dec9-13 05:02 AM jackmell 4 362 Hi, does anyone know if this function: f(x) = \sum_{k=1}^\infty \frac{(-1)^n}{x^{2k}} is representable as an... Dec7-13 08:55 PM piercebeatz 4 384 I am using the PDF for log-normal distribution, which I'm referencing off the wikipedia page: here. I am integrating... Dec7-13 07:35 PM oneamp 2 334 http://i.imgur.com/rTf1iaC.png If instead of evaluating the above line integral in counter-clockwise direction, I... Dec7-13 09:33 AM vanhees71 7 354 I am trying to compute the determinant of the Jacobian matrix of the n-dimensional spherical coordinates. i will... Dec6-13 02:24 PM hedipaldi 0 184 Given a function f(x(t, s) y(t, s)), if is possible to compact \frac{∂f}{∂t}=\frac{∂f}{∂x}... Dec5-13 08:15 AM Jhenrique 5 411 Hello guys, I am quite unsure in how to start the modeling for population. If I define y as the number of infected... Dec5-13 02:40 AM elitewarr 4 332 I have run into some situations where I need to scale a number by an infinitesimal amount and would like to know the... Dec4-13 09:33 PM tanus5 10 377 Hi, I have been stuck on a problem for a while now (3.24 part c). My attempt is as follows: Internal virtual... Dec4-13 05:35 PM c0der 2 428 Let L be a forward operator and M be its adjoint defined using the inner product (f,Lg)=(Mf,g). Typically integration... Dec4-13 05:13 PM seanobeano 0 384 Assume we have a number ##S_0##. For ##i=1..n## defineS_i=\begin{cases}(1+b)S_{i-1}\text{ with probability... Dec4-13 04:59 PM mathman 1 255 If function is ##f(-x,-y)=f(x,y)##, is then ##\int^{a}_{-a}\int^{a}_{-a}f(x,y)dxdy=0##? Thanks for answer. Dec4-13 01:53 PM LagrangeEuler 6 397 My book loves to represent the delta function as: δ(r-r')=∫-∞∞exp(i(r-r')k)dk Now I can understand this formula... Dec4-13 06:42 AM pwsnafu 1 269 Hello! Exist a general formula to idea of lagrange multiplier, a compact formula that is possible to extract the... Dec3-13 02:45 PM Jhenrique 0 202 is there a closed form solution for this double integral? \int^{2}_{1}\int^{3}_{4}\sqrt{1+4x^{2}+4y^{2}}dydx Dec3-13 11:36 AM mabauti 5 516 Is it possible to formulate the second derivate trough of a tree diagram, as we do with a first derivative? If yes,... Dec3-13 07:06 AM Jhenrique 5 408 Hello there. I recently installed the Physics Forums app and could not find the homework section in the categories so... Dec2-13 07:33 PM Mark44 2 369 Hey guys. I am having some trouble visualizing one aspect of the Second derivative test in the 2 variable case... Dec2-13 05:03 AM Phoeniyx 8 320