Stage 23 · Quadratic Functions

23.5.2 The Discriminant Counts the Crossings

23.5 Quadratic Function × Equation × Inequality

Point 2 of 5

23.5.2 The Discriminant Counts the Crossings

Core idea

Δ=b²−4ac acts like a probe: more than 0 hits two points, equal to 0 hits one, less than 0 never touches down.

Module goal. Connect the parabola's relationship with the x-axis to the roots of a quadratic equation and the solution set of a quadratic inequality.
eastmath.com · 23.5 Quadratic Function × Equation × Inequality · 23.5.2 The Discriminant Counts the Crossings