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Math Help - Integral Problem!

  1. #1
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    Integral Problem!

    ∫dx/(1-e^x)

    I have no idea what to set u equal to.

    Could someone help me begin this problem?
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  2. #2
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by r2d2 View Post
    ∫dx/(1-e^x)
    \int\frac{dx}{1-e^x}=\int\frac{dx}{1-e^x}\cdot\frac{e^{-x}}{e^{-x}}=\int\frac{e^{-x}}{e^{-x}-1}\text{ }dx...so
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  3. #3
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    Ok, So I'm stuck on why you multpilied by e^(-x)/e^(-x)
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  4. #4
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by r2d2 View Post
    Ok, So I'm stuck on why you multpilied by e^(-x)/e^(-x)
    Let u=..... That's why.
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  5. #5
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    so setting u=e^(-x), I get the integral of [du/(e^(-x)-1)]-1. Would that be correct?

    Then the integral of 1/(u-1)du = ln(u-1)?
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  6. #6
    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by r2d2 View Post
    so setting u=e^(-x), I get the integral of [du/(e^(-x)-1)]-1. Would that be correct?

    Then the integral of 1/(u-1)du = ln(u-1)?
    You forgot a negative...but
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  7. #7
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    great, so i just need to add the negative, and the c, then re-substitute the u function.

    Thanks, mate.
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