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

$a=3$.
$9x^{3}-15x\qquad$...find the GCF. $9x^{3}=(3)\cdot 3\cdot(x)\cdot x\cdot x$ $-15x=-1\cdot(3)\cdot 5\cdot(x)$ GCF=$3x$ $9x^{3}-15x\qquad...$factor out the GCF $=3x(3x^{2})-3x(5)\qquad...$apply the Distributive Property. $=3x(3x^{2}-5)$ Comparing $3x$ with $ax$, we see that $a=3$.