Key Terms

discriminant

In the Quadratic Formula, $x=\frac{\text{−}b\pm \sqrt{b^2-4ac}}{2a},$ the quantity b² − 4ac is called the discriminant.

quadratic function

A quadratic function, where a, b, and c are real numbers and $a\ne 0,$ is a function of the form $f\left(x\right)=a{x}^2+bx+c.$

quadratic inequality

A quadratic inequality is an inequality that contains a quadratic expression.