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Math Help - Double Integrals Problem

  1. #1
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    Double Integrals Problem

    I must solve the double integral -
    ∫ ∫ (x^2 + y^2) e^(-x^4 - 2(x^2)(y^2) - y^4) dy dx
    Both integrals between infinity and - infinity!
    Please help!
    Last edited by amywilliams99; March 15th 2010 at 10:59 AM.
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  2. #2
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    Sorry, error
    Last edited by tom@ballooncalculus; March 15th 2010 at 10:52 AM.
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  3. #3
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    Some one please help!
    I have attempted to use x = rcos(theta) and y=rsin(theta) but cant seem to get an answer.
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  4. #4
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    Hi. How about using polar coordinates? You know x^2+y^2=r^2 right? Then turn the crank:

    \int_{-\infty}^{\infty}\int_{-\infty}^{\infty} (x^2+y^2)e^{-(x^2+y^2)^2} dydx=\int_0^{2\pi}\int_0^{\infty}r^2 e^{-r^4}rdrdt
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