Problem $4.(1$ point$)$

The volume of the solid obtained by rotating the region bounded by

$y=x^2,y=4x$

about the line $x=4$ can be computed using the method of washers via an integral

$V={\displaystyle \underset{a}{\overset{b}{}}}?$

with limits of integration $a=$ and $b=$

The volume of this solid can also be computed using cylindrical shells via an integral

$V={\displaystyle \underset{}{\overset{}{}}}$

with limits of integration $=$ and $=$

In either case, the volume is $V=$ cubic units.