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**s3a** __Question:__

x = 1/3 * (y^2 + 2)^(3/2), 1 <= y <= 2

__Correct final answer:__

21/2 * pi

__My work:__

SA = 2pi * integral y ds = 2pi*integral (y * sqrt(1 + (dx/dy)^2)) dy

x = 1/3 * (y^2 + 2)^(3/2)

dx/dy = y*sqrt(y^2 + 2)

Then I'm stuck. Wolfram also says my answer is wrong. I used y variables and the y limits of integration and the answer differs from that of the back of the book. (http://www.wolframalpha.com/input/?i=integrate(sqrt(1+%2B+y^4+%2B+y^2)*y)+*+2pi+from +1+to+2)

Any help would be GREATLY appreciated!

Thanks in advance!