Free interactive math game: Quadratic Discriminant — How many real roots?. Part of the Functions category on MathKite.
Taken from the generator that powers this exercise. A fresh set appears every time the page is opened, and the printable worksheet holds ten of them.
The discriminant, which counts the solutions of a quadratic.
Work out b squared minus 4ac. Positive gives two roots, zero gives one, and negative gives none.
For x squared + 2x + 1, the discriminant is 4 - 4 = 0, so there is one root.
Losing a sign when a or c is negative. That flips the whole result.