Math · FREE ONLINE TOOL

Quadratic Formula Calculator

Solve quadratic equations, inspect the discriminant and find real or complex roots, with linear handling when the quadratic term is zero.

Your inputs

Calculations run in your browser. No account needed.

EXAMPLE RESULTCalculated locally
Root 1
3
Root 2
2
Discriminant
1
Clear inputs. Transparent methods.
My workspace

Calculate with your inputs to save a result or compare scenarios.

How it works

A useful distinction

Move every term before copying coefficients

For x² = 5x − 6, rewrite the equation as x² − 5x + 6 = 0, then enter 1, −5 and 6. Copying the right-hand signs directly would solve a different equation.

Reading the roots of a quadratic equation

Write the equation in the standard quadratic form before entering its coefficients, including any negative signs and a zero coefficient for a missing linear term. The roots are the input values where the expression equals zero. The discriminant helps explain whether the roots are distinct, repeated, or non-real under the supported output. A zero leading coefficient describes a different type of equation.

Quadratic roots: formula and assumptions

x = (−b ± √(b² − 4ac)) / (2a).

The discriminant identifies two real roots, a repeated root, or two complex roots. If a is zero, the equation is linear.

Worked example

Using the Quadratic roots example:

Inputs
a
1
b
-5
c
6
Method

x = (−b ± √(b² − 4ac)) / (2a).

Result

Example result

Root 1: 3

Root 2: 2

Discriminant: 1

These are illustrative inputs. Change the values to explore a different scenario.

Formula references

References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.

Common questions

What does the discriminant tell me?

A positive discriminant gives two real roots, zero gives a repeated real root, and a negative value gives complex roots.

What happens if the coefficient of x squared is zero?

The equation is no longer quadratic. The calculator treats the remaining expression as a linear or degenerate equation.

Prepared by Finflo. See our methodology and editorial policy.