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Math Help - Trying to impress my girlfriends father - working needed

  1. #1
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    Trying to impress my girlfriends father - working needed

    Hello

    I am trying to answer a question for my girlfriends father but am failing. Could someone please show the working for this. I will obviously give credit to the forum rather than taking for it myself.

    Integral (between infinity and -infinity) cos(x)/1+x(2) dx = pie/e

    Sorry I am working on Latex as I speak.

    Thanks in advance
    Matthew
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  2. #2
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    Re: Trying to impress my girlfriends father - working needed

    The LaTeX for that would be [ tex ]\int_{-\infty}\infty \frac{cos(x)}{x^2+ 1}dx[ /tex ]
    Without the spaces in [ tex ] and [ \tex ] it would be \int_{-\infty}^\infty \frac{cos(x)}{x^2+ 1}dx.

    I might feel it was wrong to get other people to help you with a problem to impress your girlfriend's father (are you planning to tell him what help you got?) except for a feeling that he is putting you on. I don't believe that can be integrated in terms of "elementary function". Writing cos(x)= \frac{e^{ix}+e^{-x}}{2} and doing it in terms of a path integral, say on a path that goes from -R to R on the real line, then along the semi-circle, in the positive imaginary half plane, of radius R from R to -R, might give something, finally taking the limit as R goes to infinity.
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  3. #3
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    Re: Trying to impress my girlfriends father - working needed

    Thank you for the LaTeX, I did say in my question that I would give all credit to the forum. The post title was being playful that's all.
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