How to use the Quadratic Formula Calculator
The quadratic calculator solves ax² + bx + c = 0 and shows the vertex.
Open the Quadratic Formula Calculator →
What you need to enter
- a
- b
- c
The formula
x = (−b ± √(b² − 4ac)) ÷ 2a. The discriminant b² − 4ac decides the number of real roots.
Worked example
Using the default values in the calculator:
- a: 1
- b: -3
- c: 2
| x₁ | 2 |
| x₂ | 1 |
| Discriminant | 1 |
| Vertex | (1.5, -0.25) |
Tips for better results
- A negative discriminant gives complex roots.
- Vertex x = −b ÷ 2a.
Common mistakes to avoid
- Entering a = 0.
- Sign mistakes with b.