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Math Help - integral of exp(-x) * x^n

  1. #1
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    integral of exp(-x) * x^n

    integration from 0 to infinity, of exp(-x) * x^n with respect to x.



    can you please help me to calculate this???
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  2. #2
    MHF Contributor MarkFL's Avatar
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    Re: integral of exp(-x) * x^n

    Define f(n)\equiv\int_0^{\infty}x^ne^{-x}\,dx and use integration by parts to show that:

    f(n)=nf(n-1) and hence:

    f(n)=n!
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  3. #3
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    Re: integral of exp(-x) * x^n

    by the way how do you post in integral typeset like that?
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  4. #4
    MHF Contributor MarkFL's Avatar
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    Re: integral of exp(-x) * x^n

    It is done using \LaTeX. There is a forum here dedicated to its usage, and there are many good tutorials online too.
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