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Homework Help: Evaluate Integral

  1. Jan 13, 2010 #1
    1. The problem statement, all variables and given/known data
    [tex]\int[/tex][tex]\frac{4}{x^2-1}[/tex]



    2. Relevant equations



    3. The attempt at a solution
    I thought I had this right...

    [tex]\frac{4}{x^2-1}[/tex] = 2 ([tex]\frac{1}{x-1}[/tex]-[tex]\frac{1}{x+1}[/tex])

    therefore,

    [tex]\int[/tex][tex]\frac{4}{x^2-1}[/tex]=2(ln(x-1)-ln(x+1))

    I then have to evaluate from 2 to 3 and I get .814, but it isn't right.
     
    Last edited: Jan 13, 2010
  2. jcsd
  3. Jan 13, 2010 #2
    Nevermind, I believe I figured it out.

    Edit: Okay, I don't understand where I went wrong. Any help please?
     
    Last edited: Jan 13, 2010
  4. Jan 13, 2010 #3
    I get log(9/4) ≈ 0.81093
    Perhaps you entered it wrong in a calculator?
     
  5. Jan 13, 2010 #4
    Oh gees... rounding error... thanks
     
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