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Homework Help: Integral question

  1. Jan 25, 2009 #1
    1. The problem statement, all variables and given/known data

    Trying to evaluate the following integral:

    ∫dx/(x√(x² - a²))

    3. The attempt at a solution

    I think I'm missing something simple. I know:

    ∫dx/(x√(x² + a²)) = - 1/a arccsch|u/a| + C

    &

    ∫dx/(x√(a² - x²)) = - 1/a arcsech(u/a) + C

    But I'm not exactly sure how to manipulate my integral into one of these forms.

    Any suggestions? Thanks
     
  2. jcsd
  3. Jan 25, 2009 #2
    [tex]\frac{1}{x(x^2-a^2)^{\frac{1}{2}}}[/tex]

    Does that help?
     
  4. Jan 25, 2009 #3

    jgens

    User Avatar
    Gold Member

    Let x = au, then dx = adu. Can you take it from there?
     
  5. Jan 25, 2009 #4
    It's just a standard integral for arcsec... :S don't know how I missed that.

    Thanks for the help
     
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