Quadratic Equation Solver

Solve ax² + bx + c = 0 with step-by-step working — formula, factoring, completing the square.

x
constant
x² − 5x + 6 = 0
Discriminant (D = b² − 4ac)1D > 0
Two distinct real roots
x₁ (5 + 1) / 2 ≈ 3
x₂ (5 − 1) / 2 ≈ 2
Vertex(2.5, -0.25)
Axis of Symmetryx = 2.5
Y-intercept(0, 6)
Parabola OpensUpward
Vertex Formy = (x − 2.5)² − 0.25
Vieta's Formulas
x₁ + x₂ =−b/a = −(-5)/1 = 5x₁ × x₂ =c/a = 6/1 = 6

What is Quadratic Equation Solver?

A quadratic equation solver is a mathematics tool that finds the roots (solutions) of any equation in the standard form ax² + bx + c = 0, where a, b, and c are real-number coefficients. Quadratic equations appear throughout algebra, physics, engineering, and finance — from calculating projectile trajectories and optimising profit functions to finding intersection points of parabolas.

This solver works through the equation using three methods and displays the full working for each, making it a useful learning aid as well as a quick computation tool. The quadratic formula method, x = (-b ± √(b² - 4ac)) / 2a, always works regardless of the discriminant value and handles all real and complex root scenarios. Factoring attempts to express the equation as (px + q)(rx + s) = 0 when integer or simple rational factors exist, which is the technique most commonly taught in secondary school algebra. Completing the square rewrites the equation in the form (x + h)² = k, providing geometric insight into the vertex of the parabola.

The discriminant (b² - 4ac) determines the nature of the roots: a positive value gives two distinct real roots, zero gives one repeated real root, and a negative value gives two complex conjugate roots. The solver displays the discriminant value and its interpretation alongside all three solution methods, helping students understand why the method produces the result it does.

How to Use Quadratic Equation Solver

  1. Enter coefficients

    Input the values of a, b, and c for your equation in the form ax² + bx + c = 0. Non-integer values are accepted.

  2. Solve the equation

    Click "Solve" to calculate the roots and the discriminant value instantly.

  3. Review step-by-step working

    See the full working for the quadratic formula, factoring, and completing the square methods.

  4. Copy results

    Copy the roots or the full working to paste into your homework, notes, or a report.

Key Benefits

Three solution methods

View results via the quadratic formula, factoring, and completing the square all at once.

Discriminant analysis

The solver shows the discriminant and explains whether roots are real, repeated, or complex.

Handles all cases

Works for positive, negative, and zero discriminants, returning complex roots when necessary.

Step-by-step working

Full working is shown for each method, making it a valuable study and revision tool.

Frequently Asked Questions

A negative discriminant means the equation has no real roots. The solver returns two complex conjugate roots in the form p + qi and p - qi, where i is the imaginary unit.

Yes. Any real number is accepted for a, b, and c, including decimals like 1.5 or negative values like -3.7.

If a is zero the equation reduces to a linear equation bx + c = 0 and is no longer quadratic. The solver will prompt you to enter a non-zero value for a.

Completing the square rewrites ax² + bx + c as a(x + b/2a)² + (c - b²/4a) = 0, then isolates x by taking the square root of both sides. It is the derivation behind the quadratic formula itself.

Related Tools