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Integrals by parts im stuck

  1. Feb 1, 2006 #1

    u=lnt dv= t^.5 dt
    du=1/t dt v= (2t^1.5)/3

    i keep on getting stuck with this integral. any help would be appreciated
  2. jcsd
  3. Feb 1, 2006 #2
    i dont want anyone to wast their time with this, this hw is due exaclty 6 hours from now, so if you dont see this thread until 5 hours after i originally posted it, dont even worry about it
  4. Feb 1, 2006 #3


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    It won't take long enough to worry about wasting time:
    You already have [itex]\int_1^4 \sqrt{t}(ln(t))dt[/itex] and
    you have set u= ln t so [itex]du= \frac{1}{t}dt[/itex] and [itex]dv= t^{\frac{1}{2}}dt[/itex] so that [itex]v= \frac{2}{3}t^{\frac{3}{2}}[/itex].

    Okay, plugging that into the integration by parts formula gives
    [tex]\int_1^4\sqrt{t}(ln(t))dt= \frac{2}{3}t^{\frac{3}{2}}ln(t)\left|_1^4- \frac{2}{3}\int_1^4 t^{\frac{1}{2}}dt[/itex]

    Why would you have any difficulty with that?
  5. Feb 1, 2006 #4

    oooooo i forgot to transfer the 2/3 to the left. thank you very much kind sir

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