## Precalculus (6th Edition) Blitzer

$\displaystyle \frac{x^{2}}{15}$
When multiplying rational expressions, we - fully factor each numerator and denominator (here, no need) - reduce the expression if there are common factors (here: none) - multiply all the numerators, multiply all the denominators. $\displaystyle \frac{x}{5}\cdot\frac{x}{5}=\frac{x\cdot x}{5\cdot 3}$ = $\displaystyle \frac{x^{2}}{15}$