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Homework Help: Help with simplifying integral

  1. Nov 27, 2011 #1
    1. The problem statement, all variables and given/known data
    We need to solve the double integral:

    6 -2/3x+4
    ∫ ∫ [12-2x-(3y/4)] dy dx
    0 0

    2. Relevant equations
    (a+b)2 = a2 + 2ab + b2


    3. The attempt at a solution
    I've got to:

    6
    (1/4) ∫ [12y-2xy-(3y2/2)] evaluated at -2/3x + 4 and 0.
    0
    6
    (1/4) ∫ [12(-2/3x + 4) - 2x(-2/3x + 4) - (3(-2/3x + 4)2/2)]
    0

    This is where I'm stuck. I could solve the rest of the integral if I could simplify this right. Sometimes, I think simplifying the integral is harder than the integration itself.
     
  2. jcsd
  3. Nov 27, 2011 #2
    This isn't right.Where did the 1/4 come from? And it's not (3y2/2), it's 3y2/8.
    Which, (1/4)(3/2)=(3/8), but then the other terms are wrong, because (1/4)12= 3, and it's not 3y.
     
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