Chapter 5 - Graphs and the Derivative - 5.1 Increasing and Decreasing Functions - 5.1 Exercises - Page 260: 7

a) $(-7;-4)$ & $(-2;\infty)$ b) $(-\infty;-7)$ & $(-4;-2)$

Step 1: Find critical points where $f'(x)=0$ Step 2: If $f'(x)$ is positive, the function is increasing Step 3: If $f'(x)$ is negative, the function is decreasing