## Algebra: A Combined Approach (4th Edition)

10$x^{4}$ + 30x
$5x(2x^{3}$ + 6) = 5x($2x^{3}$) + 5x(6) = 10$x^{4}$ + 30x since $x^{m}$ $\times$ $x^{n}$ =$x^{m + n}$, where m and n are 1 and 3, respectively. I.e.,m is the power of x in 5x and n is the power of x in $2x^{3}$.