Chapter 4 Quadratic Functions and Factoring - 4.8 Use the Quadratic Formula and the Discriminant - 4.8 Exercises - Skill Practice - Page 296: 1

Discriminant

We know that the discriminant is in the form $b^2-4ac$. If this is positive, there are two real solutions. If this is 0, there is one real solution. If this is negative, there are two imaginary solutions. Thus, the discriminant is what tells us the number and type of solutions to the quadratic equation.