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Homework Help: Shell method help.

  1. Feb 5, 2010 #1
    1. The problem statement, all variables and given/known data
    X=12(y^2-y^3) Rotation is around y=-2/5

    2. Relevant equations
    V=2pi from the integral of a to b (shellradius)(shell height) dx

    3. The attempt at a solution
    2pi (-2/5+y)(12)(y^2-Y^3)dy
    24pi (-2/5+y)(y^2-y^3)dy
    24pi (-2/5y^2+7/5y^3-y^4)dy
    24pi (-8/60y^2+21/60y^4-12/60y^5)
    answer i get is 2/5pi when i integrat from 0 to 1 the book answer is 2pi
  2. jcsd
  3. Feb 6, 2010 #2


    Staff: Mentor

    Please post the entire problem statement. Is the region being rotated bounded by some line, such as the y-axis?
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