Chapter 5 - Section 5.7 - Factoring by Special Products - Exercise Set - Page 310: 82

$V=\pi h(x+y)(x-y)$

Using $V=\pi r^2h$ or the volume of a cylinder, then the volume of the entire cylinder is $V=\pi x^2h$ and the volume of the hole is $V=\pi y^2h.$ Subtracting these two volumes, then the volume of the solid figure is \begin{array}{l}\require{cancel} V=\pi x^2h-\pi y^2h \\ V=\pi h(x^2-y^2) \\ V=\pi h(x+y)(x-y) .\end{array}