Introduction: There is a relation between the increase or decrease of a function (see Monotonicity) and the derivative.
Theorem:
Theorem:
- If $y'(x)\geq 0$ on an interval, then the function $y(x)$ is increasing on the interval.
- If $y'(x)\leq 0$ on an interval, then the function $y(x)$ is decreasing on the interval.