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Quadratic Formula Calculator

Solve quadratic equations (ax² + bx + c = 0) and find all real and complex roots. Shows discriminant, vertex, and axis of symmetry.

Real-time results 100% free No sign-up Mobile friendly

Formulas verified against authoritative sources including the CFPB and Federal Reserve. Last reviewed . Editorial policy.

Equation: ax² + bx + c = 0

1x² -5x +6 = 0

Solutions

Discriminant: b² − 4ac = 1.0000

2 distinct real roots

Root 1 (x₁)

3.000000

Root 2 (x₂)

2.000000

Vertex

(2.500, -0.250)

Axis of Symmetry

x = 2.5000

Opens

↑ Upward

Y-intercept

(0, 6.0000)

Frequently Asked Questions

What is the quadratic formula?

x = (−b ± √(b²−4ac)) / 2a. For ax² + bx + c = 0, substitute your values of a, b, and c. The ± means you get two solutions (roots) — one with + and one with −.

What does the discriminant tell you?

The discriminant is b² − 4ac. If discriminant > 0: two distinct real roots. If = 0: one repeated real root (double root). If < 0: two complex (imaginary) roots — the parabola doesn't cross the x-axis.

What is the vertex of a parabola?

The vertex is the highest or lowest point: x = −b/(2a), y = c − b²/(4a). If a > 0 the parabola opens up (minimum at vertex); if a < 0 it opens down (maximum at vertex).

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