# Identifying Stationary Points (Critical Points) for a Function

## Key Questions

• A stationary (critical) point $x = c$ of a curve $y = f \left(x\right)$ is a point in the domain of $f$ such that either $f ' \left(c\right) = 0$ or $f ' \left(c\right)$ is undefined. So, find f'(x) and look for the x-values that make $f '$ zero or undefined while $f$ is still defined there.

• Definition
A number $c$ in the domain of $f$ is called a critical number if $f ' \left(c\right) = 0$ or $f ' \left(c\right)$ is undefined.

I hope that this was helpful.