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Thread: integrate ln

  1. #1
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    integrate ln

    $\displaystyle
    \int ln(y)dy
    $

    wondering how i would integrate this
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by jvignacio View Post
    $\displaystyle
    \int ln(y)dy
    $

    wondering how i would integrate this
    This would be integrated by parts:

    Let $\displaystyle u=\ln(y)$ and $\displaystyle \,dv=\,dy$

    See how far you can get with this

    --Chris
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  3. #3
    Junior Member toraj58's Avatar
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    Lightbulb

    $\displaystyle u = \ln (x)$
    $\displaystyle dv = dx$

    according to the formula of itegrating by parts:

    $\displaystyle \color{blue}\boxed{\int udv = uv - \int vdu}$

    $\displaystyle = x\ln (x) - \int x(\frac {1}{x})dx$
    $\displaystyle x\ln (x) - x + c$
    Last edited by toraj58; Nov 3rd 2008 at 10:43 PM.
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  4. #4
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    Quote Originally Posted by toraj58 View Post
    $\displaystyle u = \ln (x)$
    $\displaystyle dv = dx$

    according to the formula of itegrating by parts:

    $\displaystyle \color{blue}\boxed{\int udv = uv - \int vdu}$

    $\displaystyle = x\ln (x) - \int x(\frac {1}{x})dx$
    $\displaystyle x\ln (x) - x + c$
    thanks mate
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