/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 24 Evaluate the double integral. ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Evaluate the double integral. $$ \int_{0}^{\infty} \int_{0}^{\infty} x y e^{-\left(x^{2}+y^{2}\right)} d x d y $$

Short Answer

Expert verified
The solution of the double integral \(\int_{0}^{\infty} \int_{0}^{\infty} x y e^{-\left(x^{2}+y^{2}\right)} d x d y\) is \(1/32\)

Step by step solution

01

Transform from Cartesian to Polar Coordinates

Since the integral is symmetric in x and y, and due to the presence of \(x^{2} + y^{2}\) in the integrand, it can be simplified by converting to polar coordinates with \(r^{2} = x^{2} + y^{2}\) and \(x = r cos(\theta)\), \(y = r sin(\theta)\), and accordingly differential area in polar coordinates will be \(dxdy = rdrd\theta\). With these transformations, the integral becomes \(\int_{0}^{\infty} \int_{0}^{\infty} r^{2} cos(\theta) sin(\theta) e^{-r^{2}} r dr d\theta\)
02

Calculate the integral

Now, the integral can be separated and factored. We get \(r^{3} cos(\theta) sin(\theta) e^{-r^{2}}\), and this bounds to 0 to \(\infty\) for r and 0 to \(\pi/2\) for \(\theta\), This integral further simplifies to equal \(1/8\)
03

Evaluate the integral over theta

Now let us calculate the remaining integral. We have already factored out the r-dependence, so we are left with \(\int_{0}^{\pi/2} cos(\theta) sin(\theta) d\theta\). This evaluates to \(1/4\)

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Study anywhere. Anytime. Across all devices.