Calculators

Quadratic Real Roots

Solve ax² + bx + c = 0 with a nonzero leading coefficient. Receive both real roots or a clear error when no real roots exist.

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How to use Quadratic Real Roots

  1. Enter “Coefficient a (nonzero)”, using the units and limits shown in its label.
  2. Enter “Coefficient b”, using the units and limits shown in its label.
  3. Enter “Coefficient c”, using the units and limits shown in its label.
  4. Select Calculate or Process. Review the result and any validation message before copying or downloading available output. Reset clears the result and restores the starting inputs.

Method & assumptions

Discriminant D = b² − 4ac; a cancellation-resistant quadratic calculation yields the two roots.

Worked example

x² − 3x + 2 = 0 has roots 1 and 2.

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Questions, answered

Does this show imaginary roots?

No. Negative discriminants are reported as having no real roots. Use a linear solver if a is zero.

Where does this calculation run?

It runs locally in your browser. Enter plain numbers without currency symbols or thousands separators; use the same currency and measurement units throughout unless a converter explicitly asks for units.