Evaluating Improper Integrals Using Polar Coordinates

In summary, we are asked to evaluate the improper integral of e^(-10(x^2+y^2))dxdy using polar coordinates and to use this result to integrate from negative infinity to positive infinity of e^(-10x^2)dx. The first integral can be split into two identical integrals and the final result for both integrals is pi/10.
  • #1
iamwilson
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Homework Statement



A.Using polar coordinates, evaluate the improper integral of e^(-10(x^2+y^2))dxdy
B. use part A to integrate from negative infinity to positive infinity of e^(-10x^2)dx

2. Homework Equations [/b]



The Attempt at a Solution



i got part A to be pi/10, but for part B i clueless, can someone please give me a hit on how to integrate it!
 
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  • #2
pi/10 looks ok. But for the second part you aren't supposed to do another integration. You are supposed to realize the first integral can be split into the product of a dx integral and a dy integral both of which look the same. Use exp(-10(x^2+y^2))=exp(-10x^2)*exp(-10y^2).
 

FAQ: Evaluating Improper Integrals Using Polar Coordinates

What is an improper integral?

An improper integral is an integral where one or both of the limits of integration are infinite or the integrand has a vertical asymptote within the interval of integration. In other words, it is an integral that does not have a finite value.

What are polar coordinates?

Polar coordinates are a system used to locate points in a two-dimensional plane by using a distance from the origin (r) and an angle from a reference line (θ). This is different from the traditional Cartesian coordinate system, which uses x and y coordinates.

How do we convert an improper integral to polar coordinates?

To convert an improper integral to polar coordinates, we substitute in the polar coordinate equivalents for x and y, such as x = rcosθ and y = rsinθ. We also need to change the limits of integration to correspond to the new coordinate system.

What is the benefit of using polar coordinates for evaluating improper integrals?

Polar coordinates can be useful for evaluating improper integrals because they can simplify the integrand and make the integral easier to solve. This is especially true for integrals where the integrand has a symmetry that aligns with the polar coordinate system.

What are some common strategies for evaluating improper integrals using polar coordinates?

Some common strategies for evaluating improper integrals using polar coordinates include using symmetry to simplify the integrand, choosing appropriate limits of integration, and using trigonometric identities to rewrite the integrand in terms of polar coordinates.

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