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Homework Help: Integration with inverse trig

  1. Feb 12, 2009 #1
    1. The problem statement, all variables and given/known data

    [tex]\int\frac{dx}{9x^{2}+1}[/tex]

    2. Relevant equations

    [tex]\frac{d}{dx}(arctan(x)) [/tex] = [tex]\frac{1}{1+x^{2}}[/tex]

    3. The attempt at a solution

    The other problems in this homework set all use the substitution rule but I can't find anything that would simplify the problem, my other guess would be to pull a (1/9) out, but then that would result in having a denominator = (x^2 + (1/9)), could someone get me on the right track, I have a feeling that I'm overlooking something obvious
     
  2. jcsd
  3. Feb 12, 2009 #2
    Try u = 3x
     
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