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Homework Help: How to integrate int x/(x^2+1)dx

  1. Dec 11, 2009 #1
    [tex]\int{\left(\frac{x}{x^2 + 1}\right)\,dx}[/tex]

    how to integrate?
    i know [tex]\int{\left(\frac{1}{x^2 + 1}\right)\,dx}[/tex]
    is tan^-1 x + C

    how am i going to start answering this question
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 11, 2009 #2

    rock.freak667

    User Avatar
    Homework Helper

    Re: Integration

    try substituting u=x2+1, du=?
     
  4. Dec 11, 2009 #3
    Re: Integration

    meaning.. i should u integration by substitution?
     
  5. Dec 11, 2009 #4
    Re: Integration

    Yes, try the u substitution.
     
  6. Dec 11, 2009 #5
    Re: Integration

    got it..
    1/2 ln |x^2 + 1| + C

    correct?
     
  7. Dec 11, 2009 #6
    Re: Integration

    That's right. One thing though: since x2 + 1 is always greater than 0, no absolute values are needed.
     
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