Find the volume if the region enclosing y=1+ sqrerootof x, x=0, y=0, and x=9 is rotated about the x axis.

Question

I used the disk method and came up with the integral: pi integral (from 0-9) of (1+sqrerootx)^2 dx, but my answer was wrong.

Answer 1

how did you integrate (1+√x)^2 ?
I would suggest you expand it first to get

1 + 2√x + x

when you integrate that you get

x + (4/3)x^(3/2) + (1/2)x^2

so my arithmetic shows

vol = pi(9 + (4/3)(27) + 81/2)
= .....

Answer 2

Oh...thanks Reiny, I threw it into my calculator wrong (forgot the parenthesis at the beginning of the function)