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

Integral of sqrt(x^2-a^2)exp(-x)

  1. May 19, 2009 #1
    New to the forum, thanks for having me.

    I've looked in tables and tried Mathmatica but have not came
    up with a formula for the integral over x of

    sqrt(x^2-a^2)exp(-x)

    If anyone could point me in the right direction I'd be appreciative.
    Thanks
     
  2. jcsd
  3. May 20, 2009 #2
    [tex]\int\sqrt{x^2-a^2}e^{-x}dx[/tex]

    Integration by parts?

    There is a standard formula for integrating [tex]\int\sqrt{x^2-a^2}dx[/tex] (that involves logs which might help later with the exponential).

    Haven't worked it out myself but that's where i'd start.
     
  4. May 20, 2009 #3

    Cyosis

    User Avatar
    Homework Helper

    You won't be able to find a primitive.
     
  5. May 20, 2009 #4
    yeah. wolfram didn't like it when i plugged it in.
     
  6. May 23, 2009 #5
    Thanks for your help. Seems integration by parts will just require further integrals
    of the form (x^2-a^2)^n/2 exp(-x). Maybe I'll just have to integrate numberially for fixed values of a.
     
  7. May 23, 2009 #6
    The integral from a to infinity can be expressed in terms of a modified Bessel function of the first kind.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Integral of sqrt(x^2-a^2)exp(-x)
  1. Integral of exp(-kx^2) (Replies: 1)

  2. Integrate sqrt(u-2) (Replies: 6)

Loading...