Quadratic Formula Lab

Drag the sliders and watch the parabola move. Feel the discriminant as a prediction: compute it first, and the roots — or their absence — are never a surprise.

Graph of y = ax² + bx + c

y = x² − 3x − 4

Mark the x-intercepts (roots) Mark the vertex

Controls

a (opens up / down) 1

Range −3 to 3, step 0.25

b −3

Range −8 to 8, step 1

c (y-intercept) −4

Range −8 to 8, step 1

When a = 0 the graph is a line, not a parabola — the quadratic formula needs a ≠ 0.

Challenges

Set the sliders, then press Check to see if your parabola meets the challenge.