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Homework Help: Bounded integral

  1. Feb 7, 2009 #1
    1. The problem statement, all variables and given/known data
    I have to take an integral of [tex]x^3/(1+x^2)[/tex] from zero to 1.48766439....(I have the number).

    2. Relevant equations
    None really.

    3. The attempt at a solution
    Well, I tried and tried, and I could not find a single way to seperate the top from the bottom. Also, I tried u substitution of both [tex]x^3[/tex] and [tex]1+x^2[/tex] but it never seemed to work out. I'm not sure if this would be good for integration of parts, since I believe that one must be able to be integrated multiple times, such as [tex]e^x[/tex], so any nudge in the right direction would help. I have the correct answer, I just would like to be able to know how to get to it. Thank you for your time.

    Last edited: Feb 7, 2009
  2. jcsd
  3. Feb 7, 2009 #2


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    Homework Helper

    Try writing it as x^2*x/(1+x^2). Now substitute u=1+x^2. Replace the x^2 in the numerator by u-1. Do you see it now?
  4. Feb 7, 2009 #3
    Ah yes! I completely forgot about that! Thank you very much, I do believe I have it now!
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