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Homework Help: Volume of Rotation

  1. Feb 2, 2015 #1
    1. The problem statement, all variables and given/known data

    How do you find the volume of the solid obtained by rotating the region bounded by the given curves about the specified lines?

    I keep getting a negative number and I"m becoming so frustrated! 11pi/30 is the answer in the textbook. Thank you so very much in advance!

    2. Relevant equations

    about y=1

    3. The attempt at a solution

    pi[(1-x^2)^2 - (1-x^(1/2))^2)]

    pi[1-2x^2+x^4-1+2x^(1/2)-x) between x=0 and x= 1

    pi[(1/5x)^5-(2/3)x^3 + (2/3)x^(3/2)-(1/2)x^2]

    pi((2/10)-(5/10)) = -3pi/10???????
    Last edited by a moderator: Feb 2, 2015
  2. jcsd
  3. Feb 2, 2015 #2


    Staff: Mentor

    I edited your post, removing most of the BBcode that you used. Physics Forums rules (https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/) discourage the overuse of special font styles in topics.
    Last edited: Feb 2, 2015
  4. Feb 2, 2015 #3


    Staff: Mentor

    You have a mistake in the line above. The coefficient 2/3 in the third term is wrong. I get what you reported to be the correct answer.
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