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Homework Help: Simple Integration problem

  1. Sep 28, 2006 #1
    How do i solve
    [tex] \int_{0}^{\infty} \lambda^2 r e^{-\lambda r} dr [/tex]

    if i were to integrate it i get
    [tex] \left[-e^{-lambda r} (1 + r \lambda)\right]_{0}^{\infty}[/tex]

    what is [tex] \lim_{r \rightarrow \infty} \frac{r}{e^r} [/tex]

    is it zero?? by virtue of e increasing faster than r ??
    Last edited: Sep 28, 2006
  2. jcsd
  3. Sep 29, 2006 #2


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    Science Advisor
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    The exponential increases faster than any polynomial.

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