Editing Shell integration (section)

=== Comparison With Disc Integration ===

Much more work is needed to find the volume if we use [[disc integration]].  First, we would need to solve <math>y = 8(x-1)^2(x-2)^2</math> for {{mvar|x}}.  Next, because the volume is hollow in the middle, we would need two functions: one that defined an outer solid and one that defined the inner hollow. After integrating each of these two functions, we would subtract them to yield the desired volume.