Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Integral of an Exponential function

  1. Jun 25, 2010 #1
    Hello every one,

    I was doing my research and then I simply struck at a point.
    The point is that i do not know how to solve the following Integral. I am not at all bad at doing math but some times I got blanked.

    so, here is the Integral,


    Integral (infinity,u) exponent^(-u) du

    result with derivation or with some reference will be highly appreciated.

  2. jcsd
  3. Jun 25, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Err, that doesn't really make sense. Do you mean,
    [tex]\int_{u}^\infty e^{-v} \, dv[/tex]
    by any chance (with the boundaries in the correct order and where the integration variable is a dummy not occurring in the integration boundary).
  4. Jun 25, 2010 #3
    ok, if it is the case then what will be the answer ?
  5. Jun 25, 2010 #4
    In a research paper, I found a solution to a similar problem.


    please look at it
  6. Jun 25, 2010 #5


    Staff: Mentor

    This is not that similar. Your problem, assuming that it is as CompuChip suggested, is
    [tex]\int_u^{\infty} e^{-v}dv[/tex]

    First, find an antiderivative using substitution.
    Second, evaluate the improper integral using limits.

    This is not a very complicated integral.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook