## Calculus 10th Edition

$-10$
To find the derivative of a function by the limit process, plug into the formula $f'(x)=\lim\limits_{h \to 0}\frac{f(x+h)-f(x)}{h}$: $f'(x)=\lim\limits_{h \to 0}\frac{-10(x+h)-(-10x)}{h}$ Simplify: $f'(x)=\lim\limits_{h \to 0}\frac{-10x-10h+10x}{h}$ $x$- and $h$-values will cancel themselves out: $f'(x)=\lim\limits_{h \to 0}\frac{10h}{h}$ $f'(x)=-10$