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Homework Help: Volume of Solid (Washer Method)

  1. Jun 8, 2012 #1
    1. The problem statement, all variables and given/known data
    Question is:
    FInd the volume for area bound between
    y = x ^ (1/3)
    x = 4y
    About the x -axis

    I found the volumes from 0 to 8 using the washer method and then multiplied that by 2 since they intersect at y = 0, -2 and 2 x = 0, 8 and -8
    Is that wrong?
    Cause my answer was double what it should have been..

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jun 9, 2012 #2


    Staff: Mentor

    What does your integral look like?
  4. Jun 9, 2012 #3
    In integrated the expression:

    x^(2/3) - ( x^2/16)
  5. Jun 9, 2012 #4


    Staff: Mentor

    Is there something in the problem that you have overlooked? For example is the region that is rotated around the x-axis supposed to be only in the first quadrant? If so, then when you doubled your answer to account for the part of the region in the third quadrant, that would cause your answer to be too large by a factor of two.

    Also, can you show the work you did in integrating?
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