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Homework Help: Double integral

  1. Jul 12, 2011 #1
    1. The problem statement, all variables and given/known data
    attachment.php?attachmentid=37128&stc=1&d=1310465399.jpg


    2. Relevant equations



    3. The attempt at a solution
    The answer is 16, but I get 12 only

    attachment.php?attachmentid=37129&stc=1&d=1310465399.jpg
     

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  2. jcsd
  3. Jul 12, 2011 #2
    The integrand becomes u^2. one 'u' from the xdx and the other from the original substitution.
     
  4. Jul 12, 2011 #3
    Oh my god. How come I can't even notice such a silly mistake.
     
  5. Jul 12, 2011 #4
    lol. happens to me a lot.
     
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