I really dont know what im doing wrong. My online homework says this is wrong but im really sure its right

Can someone look this over for me. Thank you

The region bounded by and is rotated about the line .

Using cylindrical shells, set up an integral for the volume of the resulting solid.

Equation to use:

$\displaystyle

V = \int^a_b 2\pi r h dx $

r = right - left

h = top - bottom

i sketched the graph and this is what i get from it

r = 11 - x

h = 8x - x^2 - x ---> 7x - x^2

so my final volume formula will be

$\displaystyle

V = \int^7_0 2\pi (11-x)(7x-x^2) dx

$

I evaluate that and get

$\displaystyle

2\pi(428.75)

$

V = 2693.9157

Can anyone find anything wrong with this?

Thank you for any help