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Math Help - Integration by parts...

  1. #1
    Newbie XShmalX's Avatar
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    Integration by parts...

    Integration by parts...-screen-shot-2011-03-08-20.12.32.pngReally stuck, please help?
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  2. #2
    Newbie XShmalX's Avatar
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    Ok, I now get the first one but not the second...
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  3. #3
    Forum Admin topsquark's Avatar
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    Hint:
    \displaystyle \int_{-\infty}^{\infty} \frac{1}{\sqrt{2 \pi}} z^2e^{-z^2/2}

    Rewrite this as
    \displaystyle \int_{-\infty}^{\infty} \frac{1}{\sqrt{2 \pi}} z \cdot ze^{-z^2/2}

    Integration by parts:
    \displaystyle \int p dq = pq - \int q dp

    Use \displaystyle p = z and \displaystyle dq = ze^{-z^2/2}dz

    -Dan

    Since you have the first, for the second my suggestion is to set p = z^3 and dq the same as in the first part.
    Last edited by topsquark; March 8th 2011 at 01:15 PM.
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  4. #4
    Newbie XShmalX's Avatar
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    Awesome thank you!
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