Chapter 1 - Linear Functions and Change - 1.2 Rate of Change - Exercises and Problems for Section 1.2 - Exercises and Problems - Page 15: 1

If $x\lt0$, the function is decreasing. If $x\gt0$, the function is increasing.

If $x\lt0$, then as $x$ increases, $y$ decreases, hence the function is decreasing. If $x\gt0$, then as $x$ increases, $y$ increases, hence the function is increasing.