## Precalculus (6th Edition) Blitzer

$f′(x)=\lim_\limits{ h\to 0} \dfrac{f(x+h)-f(x)}{h}$
When we are given that $y=f(x)$, then the derivative of the equation can be computed as: $f′(x)=\lim_\limits{ h\to 0} \dfrac{f(x+h)-f(x)}{h}$