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

  1. Jan 8, 2007 #1
    1. The problem statement, all variables and given/known data

    Find the following intergral...

    2. Relevant equations

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

    3. The attempt at a solution

    I can't get anywhere with this... any hints?
     
    Last edited: Jan 8, 2007
  2. jcsd
  3. Jan 8, 2007 #2
    sorry rushed the problem and did it wrong
     
    Last edited: Jan 8, 2007
  4. Jan 8, 2007 #3
    hint:

    [tex] \frac{d}{{dx}}{\arctan{x}} = \frac{1}{x^2 +1} [/tex]
     
    Last edited: Jan 8, 2007
  5. Jan 8, 2007 #4

    StatusX

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    Homework Helper

    Try adding and subtracting x^2 in the numerator.
     
  6. Jan 9, 2007 #5

    dextercioby

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    Make the substitution [itex] x=\tan t [/itex]. You'll eventually get [itex] \int \cos^2 t \ dt [/itex] which is easy to do.

    Daniel.
     
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