Quadratic equation solver
Enter the coefficients of ax² + bx + c = 0.
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How it is calculated
x = (−b ± √(b² − 4ac)) / 2a
The discriminant Δ = b² − 4ac tells you how many roots there are: two real roots if positive, one double root if zero and two complex roots if negative.
Frequently asked questions
How do you solve x² − 3x + 2 = 0?
Δ = 9 − 8 = 1, so x = (3 ± 1) / 2: x₁ = 2 and x₂ = 1.
What if the discriminant is negative?
There are no real roots: the parabola does not cross the x-axis and the roots are complex.