I have the following question:
Determine the volume of the solid when the region bounded by and the lines and is rotated about the line
I went about it as follows:
giving me a final answer of
Have I done anything wrong?
You are correctly finding the surface area of washers and integrating along the y-axis.
Your first line doesn't really require the y in brackets part.
You just need to know the two radii, which you show you do.