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Homework Help: How to solve this integration problem problem did but got wrong answer

  1. Dec 5, 2009 #1
    1. The problem statement, all variables and given/known data
    Find the volume generated by rotating the region bound by the given curves about the x axis

    2. Relevant equations
    x=1+(y-2)^2, x=2
    3. The attempt at a solution

    i solved the problem using cylinder shells method. the solution equation i got was
    integration of 2phiy(1+y^2-2y+4)dy. the upper limit of the equation i got was 3 and the lower limit was 1.
    the answer i got was 142.42 but it came out to be wrong.
    can anyone help me.
  2. jcsd
  3. Dec 5, 2009 #2


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    Science Advisor
    Homework Helper

    The length of your shell should be 2-(1+(y-2)^2), right? When I expand that, I don't get (1+y^2-2y+4). Can you check that part?
  4. Dec 5, 2009 #3
    thank you i got it now...what i did in my solution was that i didnt subtracted x=2 from the equation x= 1+ (y-2)^2.
    thanks for the help.
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