## College Algebra (10th Edition)

We find the average rate of change of $f(x)$ from 3 to 4: $\displaystyle \frac{\Delta y}{\Delta x}=\frac{f(4)-f(3)}{4-3}$ $\displaystyle =\frac{[3(4)^{2}-2(4)+4]-[3(3)^{2}-2(3)+4]}{4-3}$ $\displaystyle =\frac{44-25}{4-3}$ $\displaystyle =\frac{19}{1}$ $=19$