Answer
a) $(-\infty;-4)$ & $(-2;\infty)$
b) $(-4;-2)$
Work Step by Step
Step 1: Find critical points $f'(x)=0$
Step 2: If $f'(x)$ is positive, the function is increasing
Step 3: If $f'(x)$ is negative, the function is decreasing
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