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Thread: exponential integral

  1. June 5th 2007, 07:17 PM #1
    viet
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    exponential integral

    not quite sure how to do this one:

    \int^2_1 e^{lnu}\frac{1}{u}du
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  2. June 5th 2007, 07:18 PM #2
    Jhevon
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    Quote Originally Posted by viet View Post
    not quite sure how to do this one:

    \int^2_1 e^{lnu}\frac{1}{u}du
    substitution. let t = ln(u)
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  3. June 5th 2007, 07:29 PM #3
    ThePerfectHacker
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    Note,
    e^{\ln u}=u

    So,
    e^{\ln u}\cdot \frac{1}{u} = \frac{u}{u}=1
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  4. June 5th 2007, 07:31 PM #4
    Jhevon
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    Quote Originally Posted by ThePerfectHacker View Post
    Note,
    e^{\ln u}=u

    So,
    e^{\ln u}\cdot \frac{1}{u} = \frac{u}{u}=1
    yeah, i missed that. thanks
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