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Homework Help: Change of variables

  1. Nov 10, 2008 #1
    1. The problem statement, all variables and given/known data
    Make the appropriate change of variables and evaluate [tex]\int\int _R\(sin(9x^2+4y^2)}\;dA[/tex]


    2. Relevant equations

    R is bounded by the ellipse [tex]9x^2+4y^2=1 [/tex]

    3. The attempt at a solution

    I can't figure out what the substitution should be I tried u=9x^2 and v=4y^2 and that didn't work and I don't know where to go from here.
     
  2. jcsd
  3. Nov 10, 2008 #2

    Dick

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    Science Advisor
    Homework Helper

    How about u=3x and v=2y? Then switch to polar coordinates in u and v.
     
  4. Nov 10, 2008 #3
    ohhh... ok thanks. I should have seen that.
     
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