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Thread: where is my mitake here ,i shouldnt get 0

  1. January 21st 2011, 03:20 AM #1
    transgalactic
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    where is my mitake here ,i shouldnt get 0

    [tex]
    \int_{0}^{x}e^{-t}tdt=1e^{-t}-\int_{0}^{x}-e^{-t}=0
    [/MATH ]v'=e^{-t} u=t
    v=-e^{-t} u'=1
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  2. January 21st 2011, 03:35 AM #2
    Archie Meade
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    Quote Originally Posted by transgalactic View Post

    \displaystyle \int_{0}^{x}e^{-t}tdt=1e^{-t}-\int_{0}^{x}-e^{-t}dt=0

    v'=e^{-t}

    u=t

    v=-e^{-t}

    u'=1
    When applying integration by parts

    \int{u}dv=uv-\int{v}du

    you did not multiply uv correctly. You forgot u=t

    and got the sign wrong on v
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