## Calculus, 10th Edition (Anton)

$=-\frac{3}{x^{4}}-\frac{7}{x^{8}}.$
Restate $\frac{1}{x^{7}}$ as $x^{-7}$. Now, the power rule for derivatives ($[x^{n}]'=nx^{n-1}$) can be used to get $=-3x^{-3-1}-7x^{-7-1}=-\frac{3}{x^{4}}-\frac{7}{x^{8}}.$