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Homework Help: Integrate that by parts for integral

  1. May 3, 2008 #1
    i need help taking this integral

    [tex]\int[/tex] 9sin[tex]\sqrt{t+1}[/tex]


    help please!!!! i dont even know where to start :[
     
  2. jcsd
  3. May 3, 2008 #2

    HallsofIvy

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    First write it correctly:
    [tex]\int 9 sin(\sqrt{t+1}) dt[/tex]

    Make the obvious substitution [itex]u= \sqrt{t+1}= (t+1)^{1/2}[/itex] so that [itex]du= (1/2)(t+1)^{-1/2}dt[/itex] or 2udu= dt.
    (Equivalently, u2= t+ 1.)

    That changes your integral to
    [tex]9\int u sin(u)du[/tex]
    and you can integrate that by parts.
     
    Last edited by a moderator: May 3, 2008
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