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Homework Help: Integration by parts help just the beginning part for this one

  1. Mar 3, 2010 #1
    1. The problem statement, all variables and given/known data
    intergral from pi to 0.
    of
    (sin(3t)dt)^4






    3. The attempt at a solution

    okay so i know how to do this but when i tried substitution putting 3t=u and (1/3)du= dt i always came with the the wrong coefficient at the end with the answer and so i would multiply it wrong. but then when i do not use u/du substitution everything works well? why is that? what is the difference? and im using u/du substitution improperly or something?
     
  2. jcsd
  3. Mar 3, 2010 #2
    Are you correctly changing the limits?
     
  4. Mar 3, 2010 #3
    i didn't need to change it because i just plugged back in the variables u with 3t. just wondering it should be correct even if i substitute right?
     
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