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Quadratic Equation Solver

Solve a quadratic equation from coefficients a, b, and c. Review the discriminant and the rounded real or complex roots.

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How Quadratic Equation Solver works

The discriminant determines which form of the quadratic root calculation applies.

The solver calculates b squared minus four times a times c. A nonnegative discriminant is used in the quadratic formula for real roots; a negative one is represented as a real part plus or minus an imaginary component.

Coefficient a must be nonzero. Results are rounded for display; exact algebraic forms are not generated.

Conceptual quadratic coefficients feeding a discriminant check and real or complex root outcomes.
The discriminant determines whether the quadratic roots are real, repeated, or complex.

How to use Quadratic Equation Solver

Enter coefficients for a quadratic written with all terms on one side of the equation.

Enter the three equation coefficients

Enter a, b, and c from a quadratic written in the form ax squared plus bx plus c equals zero. Keep coefficient signs intact. The a coefficient must be nonzero, because this form does not switch to solving a linear equation.

Coefficient a
Quadratic Equation Solver native input panel with the actual Coefficient a, Coefficient b, Coefficient c settings used for this example.
Configure Coefficient a, Coefficient b, Coefficient c; select Calculate.

Calculate the discriminant and roots

Select Calculate and read the root result and its type. The discriminant decides whether the answer has two real roots, one repeated real root, or complex conjugates. Check the entered signs if the expected type differs from the result.

0 ± 1i
Quadratic Equation Solver actual result panel showing 0 ± 1i.
Submitted result: 0 ± 1i. Discriminant: -4.

Review the rounded components

Read the discriminant and supporting roots or real and imaginary components. Values are rounded to four decimal places for display; exact radical forms are not generated. Keep the original coefficients when checking a rounded root in another calculation.

Discriminant
Quadratic Equation Solver actual discriminant region and result note after submitting the pictured settings.
Review Discriminant, Real part, Imaginary magnitude in this Quadratic Equation Solver example. Read the result note.

Quadratic formula examples with real and complex roots

Use explicit coefficient examples so the equation being solved remains clear.

Check two real roots of a factorable quadratic

The hypothetical equation x squared minus five x plus six equals zero has roots two and three. Enter a as one, b as negative five and c as six. This is a direct check of coefficient signs and the two root result.

Abstract input values and a mathematical worksheet.
Start with the values. Concept illustration.

Inspect a repeated root

Use coefficients that produce a zero discriminant to see the repeated real root case. The result label distinguishes it from two distinct roots. A numerical display alone can make equal roots look like an omitted answer unless that label is retained.

Two calculation examples shown for comparison.
Compare a second example. Concept illustration.

Review a complex root result

For a negative discriminant, read the real part and imaginary magnitude together with the conjugate pair. The output uses rounded numerical values. It does not generate exact symbolic expressions or explain a full algebraic derivation for the entered equation.

A calculation and supporting explanation represented conceptually.
Explain the calculation. Concept illustration.

Use rounded roots with the original equation

Read the root type and rounding with the original coefficients.

Real roots are displayed to four decimal places. Substituting a rounded root into the original equation can leave a small residual, so the display should not be treated as an exact symbolic expression.

The discriminant determines the root type in the entered numerical model. Complex roots are given as a conjugate pair. Exact radicals, symbolic simplification and graph plotting are not part of this tool's output.

A mathematical result connected to the values used to calculate it.
Read the result with its inputs. Concept illustration.

Check signs and missing terms

Check coefficient signs and the nonzero quadratic term before solving.

A zero a coefficient is rejected because the equation would no longer be quadratic. Use the equation's correct form rather than entering an arbitrary nonzero value to get a result. Preserve minus signs when moving terms.

If the answer differs from a worked example, compare every coefficient and its sign first. The calculator does not parse variables or an equation string. Keep numerical precision in mind when checking a displayed root by substitution.

Values and units reviewed before relying on a mathematical result.
Check values and units. Concept illustration.

Use Quadratic Equation Solver

Solve a quadratic equation from coefficients a, b, and c.

Calculate

Quadratic Equation Solver: common questions

Answers about using Quadratic Equation Solver and understanding its results.

What if the discriminant is zero?

The equation has one repeated real root.

Can it show complex roots?

Yes. A negative discriminant is displayed as a real part plus or minus an imaginary part.

Can a be zero?

No. A zero a coefficient makes the equation non-quadratic. This form asks for a nonzero a rather than switching to a linear solver.

Does it return exact radicals?

No. Roots are formatted to four decimal places. Check rounding before using the displayed values in further calculations.