I'm having trouble coming up with the correct solution to a number of these questions.. This is one I've been stumped on..(adsbygoogle = window.adsbygoogle || []).push({});

Find the Volume of the solid that results when the region enclosed by the given curves is revolved about the x-axis.

y = sqrt(25-x^2), y = 3

Since I believe it is a washer method, what I did was:

V = int pi[f(x)]^2 - [g(x)]^2 dx

= pi int{-5to5} [25-x^2] - [9] dx

= pi int{-5to5} [25x-x^3/3] - [9x]

= pi [(-125) + (125/3) + (45)] - [(125) - (125/3) - (45)]

= pi (365/3) - (115/3)

= 250pi/3

The book says 256pi/3, which part am I doing wrong?

Any help is greatly appreciated.

Thanks.

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# Help with Volumes by slicing

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