## Precalculus: Mathematics for Calculus, 7th Edition

To multiply two rational expressions, we multiply their numerators together and multiply their denominators together. So, $\frac{2}{x + 1}$ $\times$ $\frac{x}{x + 3}$ is the same as $\frac{2x}{(x + 1)(x + 3)}$.
$\frac{2}{x + 1}$ $\times$ $\frac{x}{x + 3}$ = $\frac{2 \times x}{(x + 1) \times (x + 3)}$ = $\frac{2x}{(x + 1)(x + 3)}$.