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Definite integral with x^2+c in the denominator

  1. Jan 30, 2014 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations

    solve the definite integral

    [tex]\int_{2.6}^{5.5} \frac{1}{x^2+9}dx[/tex]

    3. The attempt at a solution

    ln(5.5^2+9)-ln(2.6^2+9) doesn't seem correct
     
  2. jcsd
  3. Jan 30, 2014 #2

    king vitamin

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    Gold Member

    Can you show your steps in getting that solution? What did you get for the antiderivative of the integrand?
     
  4. Jan 30, 2014 #3

    Dick

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    Science Advisor
    Homework Helper

    If you take the derivative of log(x^2+9) you will not get 1/(x^2+9) (at least if you don't forget the chain rule). You need a trig substitution to do that integral.
     
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