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Homework Help: Integral trig substitution

  1. May 12, 2010 #1
    integral of x/(x2+2x+2)dx

    first thing i did was complete the square to get

    x/((x+1)2+1

    i tried then having x+1 = tanx but that didnt work out

    because of the x on top i cant just set w = x+1

    what would the right substitution be?

    any hints or help would be appreciated
     
  2. jcsd
  3. May 12, 2010 #2
    apiwowar - try one more substitution, u = (x+1). This will yield two terms in numerator, thus two fractions, for which you should be able to integrate separately with a little more manipulation.
     
  4. May 13, 2010 #3

    Cyosis

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    Homework Helper

    Using the substitution [itex]x+1=\tan u[/itex] will work just fine. However the substitution in post #2 will make it easier. Show us where you got stuck.
     
  5. May 13, 2010 #4
    i did the substitution that the first guy suggested and got 1/2ln((x+1)2+1) - arctan(x+1)

    is that right?
     
  6. May 13, 2010 #5
    That is what I obtained (don't forget constant of integration).
     
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