Mathematics for IGCSE & O level - Equations (Section 6 - No. 33)
What does it mean if the discriminant (b² - 4ac) of a quadratic equation is equal to zero?
There are two distinct real roots.
There is one real root (a repeated root).
There are no real roots.
There are two complex roots.
Explication
A discriminant of zero signifies that the quadratic equation has one repeated real root.