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Surface area about axis

  1. Apr 15, 2015 #1

    y=x2/4 - ln(x)/2 from 1=<x<=2

    rotated about the y-axis.

    I did the equation rotating about the x axis via 2pi* integral (f(x)*sqrt(1+f'(x)^2)) dx
    with dy/dx = x/2 - 1/2x

    but the question calls for rotation about y and i cant seem to rearrange the equation to isolate for x in terms of y.

    Any ideas?

  2. jcsd
  3. Apr 15, 2015 #2


    Staff: Mentor

    Closed. Homework-type questions should be posted in the appropriate Homework sections.
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