Quadratic Equation Solver

Solve any quadratic equation ax² + bx + c = 0. Calculates real and complex roots, discriminant, vertex, and axis of symmetry.

15x +6= 0
Discriminant (Δ = b² − 4ac)1Two distinct real roots
Root x₁3
Root x₂2
Vertex (h, k)(2.5, -0.25)
Axis of Symmetryx = 2.5
Parabola OpensUpward ↑

Step-by-step Solution

  1. Identify: a = 1, b = -5, c = 6
  2. Compute discriminant: Δ = b² − 4ac = -5² − 4×1×6 = 1
  3. √Δ = √1 = 1
  4. x₁ = (−-5 + 1) / (2×1) = 3
  5. x₂ = (−-5 − 1) / (2×1) = 2
  6. Vertex: h = −b/(2a) = 2.5, k = -0.25

The Quadratic Formula

For ax² + bx + c = 0, the solutions are:

x = (−b ± √(b² − 4ac)) / (2a)

The discriminant Δ = b² − 4ac determines the nature of the roots:

  • Δ > 0 — Two distinct real roots
  • Δ = 0 — One repeated real root (the parabola touches the x-axis)
  • Δ < 0 — Two complex conjugate roots (no real solution)

The vertex of the parabola is at h = −b/(2a), k = c − b²/(4a).

Frequently Asked Questions

x = (−b ± √(b² − 4ac)) / (2a). It gives the values of x where ax² + bx + c = 0.

The discriminant Δ = b² − 4ac tells us how many real solutions exist. Δ > 0: two real roots. Δ = 0: one repeated real root. Δ < 0: two complex (imaginary) roots.

The vertex is the highest or lowest point of the parabola. Its x-coordinate is h = −b/(2a) and y-coordinate is k = c − b²/(4a).

When a = 0, the equation becomes linear (bx + c = 0), not quadratic. The quadratic formula requires a ≠ 0.

Related Tools