Substitution Definition and 797 Threads

Homework Statement Integrate the following via substituion: t = r(r2 -4)5[/sub] The Attempt at a Solution I tried numerous variations. I tried substituting in u = r^(2/5) -4r^(1/5) also u=r^2 -4 and u = r^(11/5) -4r^(1/5) NONE of these substitutions worked because of the lone r...

Homework Statement See below. 2. The attempt at a solution Hey there, apologies for doing so, but I don't know how to use latex on this board (it doesn't show me anything when I hit preview, so I had to make a picture for the sake of cleanness. imgur.com/WzrAR.png The first line is the...

$\displaystyle (3)\;\; \int \frac{1}{\sqrt{1-x^4}}dx$

Homework Statement Calculate the following integral: \int{\frac{\sqrt{x+1}}{x+5}dx} \ , x ≥ 1 By using the following substitution: t=\sqrt{x+1} Homework Equations Well using the integration by substitution formula. The Attempt at a Solution So I have t=\sqrt{x+1}...

Homework Statement Proof d/dx e^x=e^x, use e=limit (1+1/h)^h h->infinity Show how that implies d/dx e^x=e^x t Homework Equations The Attempt at a Solution Ive tried using chain rule--wasnt accepted Also, I did e=(1+h)^[1/h]-->e^h=1+h, then reduced to e^x, still didnt accept...

Dear all, I have a question about the variable substitution in Langevin equation and Fokker-Planck equation and this has bothered me a lot. The general Langevin equation is: $$\frac{dx}{dt}=u(x)+\sqrt{2 D(x)}\eta(t)$$ and the corresponding Fokker-Planck equation is thus: $$\frac{\partial...

Homework Statement I was working on a problem set involving greens theorem and I came across this peculiar trig substitution. I was just wondering how it came about as I couldn't find anything like it on Wikipedia's page. sin^4(t)cos^2(t) + cos^4(t) sin^2(t) = cos^2(t)sin^2(t) The...

Hello, everyone. So, this is my first time doing Chemistry at school and today my teacher assigned each student a topic in Chemistry to research and give a short presentation on it on Monday. He assigned me the topic of, Substitution Polymers. So, tonight I thought I might do some research on...

Hello again, I have a question about a trigonometric substitution problem that I am struggling with. I was able to get the correct answer, which I know is correct because of Wolfram verification, and my school has a way of showing an example which showed the steps... Anyway, see below...

pete078421's question from Math Help Forum, Hi pete078421, Using the given substitution you get, \[\frac{d^2z}{dt^2}+2z=4t^2\] First we shall find the complementary function for this differential equation. The auxiliary equation is, \[m^2+2=0\] \[\Rightarrow m=\pm i\sqrt{2}\] Therefore...

Homework Statement Solve using an appropriate substitution ydx+(1+ye^x)dy=0 Homework Equations N/A The Attempt at a Solution u=y du/dx=dy/dx u+(1+ue^x)du/dx=0 This is where it gets really sticky for me. I can't see it being a separable variable problem because it seems...

Homework Statement The Attempt at a Solution if x2 = u - 1, and if x3 = x2 * x, then x3 should equal (u-1)x, not .5(u-1). I'm assuming that they got u.5 because (x2+1).5 = (u-1+1).5 which is the same as u^.5

I would think because of this The following problem: At this stage they should use integration by parts: However, maybe integration by parts is only useful when one of the parts is e^x ln or a trigonometric formula.

Homework Statement Using a suitable substitution find the solution to: ∫ (x+2)50(x+1)dx Homework Equations The Attempt at a Solution I can't find a solution to this using substitution. Wolfram alpha give an answer that is too long to be calculated by hand. Can anyone work...

Hello, I am trying to integrate 1/(x^2-1). Apparently this can be solved by using trig substitution involving tan ? Can someone please help me to understand how to go about it. Thanks kindly for any help.

So a question for a test I just had was integrate by substitution: Sin(x)e^Cos(x). I did something like this: Let u=Cos(x) du=-sin(x) dx ∫sin(x)e^Cos(x) dx = ∫-e^u du =∫-e^Cos(x) du...

Homework Statement Evaluate (using a substitution) \int\int_{B}x^{2}+2y dxdy where B=\{(x, y) | x^{2}+y^{2}≤4\} The Attempt at a Solution I attempted a solution using polar coordinates, so the integral becomes \int\int_{B_{ρθ}}(ρ^{2}cos^{2}(θ)+2ρsin(θ)) ρ dρdθ, and the integration...

Hi, Firstly: This is not a homework Q. Check my previous posts, you will see the stuff i ask is for my own genuine learning. Let: \vartheta = (\Omega*t)/2 Now I have: d^2x/dt^2 And I want to sub in for t. So: d/dt = d\vartheta/dt * d/d\vartheta (Basic chain rule) I can work out that...

Suppose we lived in significantly hotter conditions that what we live in right now (or lower pressure)... could organisms composed of Tin or Lead as opposed to carbon, Bismuth/Antimony as opposed to Nitrogen, Selenium and Tellurium as opposed to oxygen and sulfur respectively, and substances...

Really not sure... Does anyone know an appropriate substitution? The whole problem is: Find the substitution that simplifies the differential equation x(dy/dx) + y = e^(x*y)

I am trying to solve an equation that involves substitution. I was given k= 7 in the equation n=k+c i was also given n=2^c-1 I figured that 7+c could be substituted into the equation as n, so I got 7+c=2^c-1 and therefore c=2^c-8. The problem is that the answer I want is c=4...but...

Use Green's THM to calculate the line integral ∫C(F<dot> dx), where C is the circle (x-2)2 + (y - 3)2=1 oriented counterclockwise, and F(x,y)=(y+ln(x2+y2), 2tan-1(x/y)). Green's THM ∫∂SF<dot>dx=∫∫S(∂F2/∂x) - ∂F1/∂y) I tried doing it by brute force. I took the partials and put them...

Homework Statement \sin\theta\frac{d^2y}{d\theta^2}-\cos\theta\frac{dy}{d\theta}+2y\sin^3\theta=0Homework Equations Use the substitution x=\cos\thetaThe Attempt at a Solution I started off by listing: x=\cos\theta\\ \frac{dx}{d\theta}=-\sin\theta\\ \frac{d^2x}{d\theta^2}=-\cos\theta\\ But...

The problem is to solve the integral of : dx / (x^2(9-4x^2)^(1/2)) using trig substituition, which I really don't understand. Formula's that are useful: The integral table Integral 1/(u^2(a^2-u^2)^(1/2))= -((a^2-u^2)^(1/2)) / (ua^2) Work so far: Figuratively banging my head...

Homework Statement Original problem is differential equation dy/dx=(x+2y)/(3y-2x) This is part of solving differential equation. x(dv/dx) = (1+4v-3v^2)/(3v-2) so one way of solving, I take out the negative sign x(dv/dx) = -((3v^2-4v-1)/(3v-2)) , separate and bring over...

The stupid question of the day. Is it fair to say that\frac{du}{dx} = \frac 1 {dx/du} since this comes (I think) from the chain rule, \frac{dx}{du} \frac{du}{dx} = \frac{dx}{dx} = 1 Which means that, when integrating by substitution, I can choose to do either of \int f(u) du = \int...

Homework Statement find ∫x/√(x+1).dx with limits 1 & 0 using substitution x = u^2 -1 Homework Equations The Attempt at a Solution dx = du x = u^2 -1 u = √( x+1) sub limits of 1 & 0 into u. Hence new limits of √2 & 1 Therefore, ∫ u^2 -1/ u = ∫ u - 1/u =...

Homework Statement Evaluate. \int(4-y)\sqrt{4-y^{2}}dy I have the solution using CAS software here: 2y\sqrt{4-y^{2}}+8sin^{-1}\frac{y}{2}+\frac{1}{3}(4-y^{2})^{3/2} but I need to do this by hand. I have researched the usual trig methods but am having some difficulty. Can...

Homework Statement Find ∫e^x/ (1+e^2x). dx , with limits ln 2 & 0 given u= e^x Homework Equations The Attempt at a Solution u= e^x du/dx = e^x dx= du/e^x sub limits of ln2 & 0 → u Hence, limits 2 & 1 Therefore, ∫u* (1+e^2x)^-1* du/e^x = ∫ u/ (u + e^3x) = ∫...

[b]1. Homework Statement Evaluate ∫ 3x /(3x+1)^2.dx , with limits 1 & 0 using the sustitution u = 3x+1 Homework Equations The Attempt at a Solution u= 3x+1 du/dx = 3 dx = du/3 Therefore, ∫ 3x*(u)^-2 * du/3 = ∫ x* (u)^-2 Since u = 3x +1 Therefore, x =...

Say we are solving an indefinite integral ∫x√(2x+1) dx. According to the textbook, the solution goes like this. Let u = 2x+1. Then x = (u-1)/2. Since √(2x+1) dx = (1/2)√u du, x√(2x+1) dx = [(u-1)/2] * (1/2)√u du. ∫x√(2x+1) dx = ∫[(u-1)/2] * (1/2)√u du. <= What justifies this?? The...

Homework Statement Find the integral of 3x* (2x-5)^6*dx, let u= 2x -5. Homework Equations Im not sure if i am meant to use integration by parts or not?? I was able to do previous questions of the topic just using u sub to get rid of the first x variable. The Attempt at a Solution...

Homework Statement make a u- substitution and integrate from u(a) to u(b) Homework Equations ∫[0,1] √(t^5+2t) (5t^4+2) dt The Attempt at a Solution u= t^5+2t du= 5t^4+2 u(1)=2 u(0)=0 ∫[0,1] √(u) du (2/3)(u)^3/2+c l[0,2] (2/3)( 0^5+2(0))^3/2- (2/3)(2^5+2(2))^3/2 0+...

Calculate the elasticity of substitution between y and x for F(x,y) = 10x^2 + 15y^2 I was able to calculate the Marginal Rate of Substitution as 20x/30y but I'm not sure how to proceed past that. The answer in the book is -1. Any and all help appreciated!

Homework Statement use substitution to evaluate the integral Homework Equations 1)∫ tan(4x+2)dx 2)∫3(sin x)^-2 dx The Attempt at a Solution 1) u= 4x+2 du= 4 (1/4)∫4 tan(4x+2) dx ∫(1/4)tan(4x+2)(4dx) ∫ (1/4) tanu du (1/4)ln ltan(u)l +c 2) u=sinx du= cosx or u=x du = 1 ?

I need a new calculator as a replacement for my (now deceased) beloved HP 32Sii. What would be the next best thing?

I feel as if I have made the correct substitution, what am I missing? See Attachment. Thanks, Dane

I was messing around proving the area of a circle using trigonometric substitution. However, I ended up with area = -πr^2. In my integral I ended up using trigonometric substitution and setting x = r*cos(theta) However, this yields x = -r*sin(theta)*d(theta). When that's substituted...

Homework Statement The Attempt at a Solution I don't see why the √v disappears in this step I understand how they got the 20/3, because they integrated, but if they're integrating then I would think v^-1/2 would become (v^1/2)/(1/2)

Homework Statement Why does the 3x^2 disappear? Doesn't it play a role in the answer?

Homework Statement here is the answer The Attempt at a Solution My book doesn't do a good job of explaining the substitution rule. here is their explanation: using the solution manual and looking at how they got the answer to other questions, I've written down my own...

Homework Statement The following is to be evaluated using substitution or partial integration. \int\frac{(2x-1)}{e^{\arctan(x)}}\,dx (It's supposed to be e^(arctan(x)) but I'm new to LaTeX and can't quite figure out how I would input it correctly) (Fixed it for you.)[/color]...

Homework Statement \int\frac{\sqrt{16+x^{2}}}{x} Homework Equations The Attempt at a Solution set x=4tant dx=4sec^{2}t dt so after plugging in and using a quick trig identity I get: \int\frac{16(sec^{2}t)*4sec^{2}t dt}{4tant} Then after a quick cleanup: 16*\int...

Homework Statement I got to a place in a problem where I need to do a sticky integral, and I'm hoping I can use a trig substitution. If not, I will need to solve the main problem another way :( \int_0^\infty \sqrt{1+(e^{-\theta })^2} \; \mathrm{d} \theta Homework Equations 1+\tan ^2...

Substitution method with Integration by Parts? Homework Statement Evaluate the integral... ∫x^3[e^(-x^2)]dx Homework Equations ∫udv=uv-∫vdu The Attempt at a Solution I first tried using integration by parts setting u and dv equal to anything and everything. This seemed to make...

I'm working through rewriting the gamma function as an infinite product, but my question is just about a specific substitution that was made in my textbook. They took the equation: \Gamma_ n(z)=\int_0^n t^{z-1} (1-\frac{t}{n}) ^ndt for Re(z)>0 and n greater than or equal to 1. and made the...

Hi, I'm learning about Laplace and I was wondering what substitution is when using laplace. Just say you have to find the laplace transform of {x^4 e^4x} I know what the individual transforms are = 4!//S^5 and 1/S-3 but how do you kinda smush them together, apparently that's...

Homework Statement Hi! In an assignment I have reached an integral that has the form: \int\frac{A+Bx+Cx^2}{Dx+Ex^2} where A-E are constants, the integration variable is x and the limits are 0 to 1. I'm supposed to remove the singularity at x=0 by substitution. A-E have values but they're...

Homework Statement 2 ∫ dx / (x+1)√[2x(x+2)] 1 Homework Equations Let x = tan θ if √(a^2 + x^2) Where a = constant The Attempt at a Solution 2 ∫ dx / (x+1)√(2x)√(x+2) 1 2 1/√2 ( ∫ dx / (√x)(x+1)[√(x+2)] 1 Now make all x...

Homework Statement To show that \int_{0}^ \frac{\pi}{2}\sqrt{cos\theta}sin^3(\theta) d\theta = 8/21 The Attempt at a Solution The above expression was simplified as \int_{0}^ \frac{\pi}{2}\sqrt{cos\theta}sin^2(\theta) sin(\theta) d\theta \int_{0}^...