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Math Help - Need help solving simple integral

  1. #1
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    Need help solving simple integral

    Wolfram Alpha gives an answer of \frac{1}{2}, but it doesn't give the steps. Can someone walk me through the problem or a similar problem? I believe I need to use integration by parts but I keep getting stuck.

    Thanks

    \int_{0}^{\infty}\frac{3x}{(1+x)^{4}}dx
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  2. #2
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    Re: Need help solving simple integral

    Quote Originally Posted by downthesun01 View Post
    Wolfram Alpha gives an answer of \frac{1}{2}, but it doesn't give the steps. Can someone walk me through the problem or a similar problem? I believe I need to use integration by parts but I keep getting stuck.

    Thanks

    \int_{0}^{\infty}\frac{3x}{(1+x)^{4}}dx
    try the substitution u = x+1
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  3. #3
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    Re: Need help solving simple integral

    Thanks. I just got it myself using integration by parts.

    u=3x, du=3dx  , dv=\frac{1}{(1+x)^{4}}, v\frac{-1}{3(1+x)^{-3}}
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