## Algebra 1: Common Core (15th Edition)

a. $2\pi x(x+3)^{2}$ b. $r=x+3$
a. $2\pi x^{3}+12\pi x^{2}+18\pi x=$ ...factor out the GCF. $=2\pi x(x^{2}+6x+9)$ ...write $(x^{2}+6x+9)$ as a square of a binomial. $=2\pi x(x+3)^{2}$ b. If $V=\pi r^{2}h$, and $V=2\pi x(x+3)^{2}$, then $h=2x,\ \pi=\pi$, which means that $r^{2}=(x+3)^{2}$ $r=x+3$