Find the volume bounded by y=4x^3, x+y=5, and x=0 rotated around the x-axis. I used the Washer Method and got π(25-10x+x^2-16x^6)dx [0,4], but I got a ridiculously large number when I solved for the whole thing. The answer is supposed to be 379π/21

Question

irishboy123 · Answer

answer seems fine :p

phi · Answer

I used the Washer Method   (I assume that means you integrated over dy?)
if so, notice you have to break the problem into two integrals because the "right boundary" changes.  As Irish shows, it makes more sense to use the shell method.

irishboy123 · Answer

yeah, i did the other way first and it is bit more of a pain