When the discriminant is zero, the quadratic equation has:

1. Each sign of the discriminant gives a different root count. 2. The discriminant determines the number of solutions. 3. When the discriminant is positive the equation has two solutions. 4. When the discriminant is zero the quadratic equation has one solution. _Source: OpenStax Elementary Algebra 2e (CC BY 4.0), Ch 10 'Quadratic Equations', sections 10.1-10.5_