## Precalculus (6th Edition) Blitzer

$(-3,4)$
Step 1. Rewrite the inequality as $x^2-x-12=(x-4)(x+3)\lt0$ Thus the boundary points are $x=-3,4$ Step 2. Using test points to examine the signs of the left side across the boundary points, we have $...(+)...(-3)...(-)...(4)...(+)...$; thus the solutions are $(-3,4)$ Step 3. We can graph the above solution on a real number line as shown.