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Quadratic Equation Solver

Looking for a quadratic equation solver with steps formula? This free tool gives you both roots, discriminant and vertex of any quadratic equation. Just enter your numbers and press Calculate — results are instant.

How to Use This Quadratic Equation Solver

A quadratic equation has the form ax² + bx + c = 0, and its roots come from the quadratic formula: x equals minus b, plus or minus the square root of the discriminant, all over 2a. The discriminant (b² − 4ac) tells you what kind of roots to expect: positive means two real roots, zero means one repeated root, and negative means two complex roots. The calculator also gives the vertex, the turning point of the parabola.

Formula Used

x = (−b ± √(b² − 4ac)) ÷ 2a. The discriminant b² − 4ac tells you if the roots are real or complex.

Worked Example

Example: Solve x² − 5x + 6 = 0 (a=1, b=−5, c=6)

  1. Discriminant = b² − 4ac = 25 − 24 = 1.
  2. Roots: x = (5 ± √1) ÷ 2, giving x = 3 and x = 2.
  3. Vertex: x = −b ÷ 2a = 2.5, and y = 2.5² − 5 × 2.5 + 6 = −0.25, so the vertex is (2.5, −0.25).

Root 1 (x₁): 3.000000

Frequently Asked Questions

What does the discriminant tell me?

The discriminant (b² − 4ac) tells you what kind of roots to expect before you solve: positive means two different real roots, zero means one repeated root, and negative means two complex roots.

What if the discriminant is negative?

The equation has no real roots — its graph never touches the x-axis. The calculator then gives the two complex roots, in the form a ± bi.

How can I check the answer?

Factor it. For x² − 5x + 6 = 0, the roots 2 and 3 give the factors (x − 2)(x − 3), which multiplies back to x² − 5x + 6.

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