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

  1. #1
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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$\displaystyle ]v'=e^{-t}$ u=t
    $\displaystyle v=-e^{-t}$ u'=1
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  2. #2
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    Quote Originally Posted by transgalactic View Post

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

    $\displaystyle v'=e^{-t}$

    u=t

    $\displaystyle v=-e^{-t}$

    u'=1
    When applying integration by parts

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

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

    and got the sign wrong on $\displaystyle v$
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