Solve any quadratic equation ax² + bx + c = 0 to find its real or complex roots, plus the discriminant, vertex and axis of symmetry. Free and instant.

x2 +
x +
= 0
Enter the coefficients a, b and c. Coefficient a cannot be zero for a quadratic.
Roots
Nature of roots
Discriminant (b² − 4ac)
Vertex (x, y)
Axis of symmetry
Roots use the quadratic formula. A positive discriminant gives two real roots, zero gives a repeated root, and a negative value gives complex conjugate roots.

About Quadratic Equation Solver

The quadratic equation solver finds the roots of any equation in the form ax² + bx + c = 0. Enter the three coefficients and it returns the real or complex roots, the discriminant, the vertex of the parabola and its axis of symmetry.

It applies the quadratic formula, x = (−b ± √(b² − 4ac)) ÷ 2a, and classifies the result by the discriminant: positive gives two distinct real roots, zero gives one repeated root, and negative gives two complex conjugate roots — which the solver displays in full rather than reporting “no solution”.

Beyond homework checking, the vertex and axis of symmetry make it useful for graphing parabolas, optimization problems and physics questions like projectile motion, all free and instant in your browser.

How to use Quadratic Equation Solver

  1. Enter coefficient a — it cannot be zero for a true quadratic.
  2. Enter coefficients b and c, using negatives where the equation subtracts.
  3. Read the roots and the nature of the roots — two real, one repeated, or complex conjugates.
  4. Check the discriminant (b² − 4ac), the vertex (x, y) and the axis of symmetry for graphing.

Frequently asked questions

The sign of b² − 4ac determines the root type before you solve anything: positive means two distinct real roots, zero means one repeated real root, and negative means a pair of complex conjugate roots.

Yes. When the discriminant is negative, it reports both complex conjugate roots in a ± bi form instead of stopping at “no real solutions”, which is what you need for full algebra coursework.

The equation is no longer quadratic. The solver detects this and treats bx + c = 0 as a linear equation, or flags the input as not an equation when b is also zero.

The vertex (−b ⁄ 2a, and its y-value) is the parabola's highest or lowest point, and the axis of symmetry is the vertical line through it. Both are essential for sketching the graph or solving max/min problems.

Set a = 1, b = −5 and c = 6. The solver returns the roots 2 and 3. Always move every term to one side first so the equation matches ax² + bx + c = 0.

Need help?
Found an issue with this tool? Let our team know.
Report an issue

Add this free tool to your own website — copy and paste the code below.