x = 1 + 2y^2, 1 <= y <= 2 so I figure out dy/dx = 4y 2PI integral[ (1+2y^2)*sqrt(1+16y^2)] At this point, I've tried so many different integration techniques but I can't find the antiderivative.
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Originally Posted by s3n4te x = 1 + 2y^2, 1 <= y <= 2 so I figure out dy/dx = 4y 2PI integral[ (1+2y^2)*sqrt(1+16y^2)] At this point, I've tried so many different integration techniques but I can't find the antiderivative. I assume the rotation is around the y-axis ....? Try the substitution $\displaystyle y = \frac{1}{4} \sinh u$.
sorry, it's around the x-axis, i thought it was y until i re-read the question. LOL, it's really simple when it's around the x-axis doh.
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