About the quadratic equation calculator
The quadratic formula solves any equation of the form ax² + bx + c = 0. The discriminant, b² − 4ac, tells you whether there are two real roots, one repeated root, or two complex roots.
How to use this calculator
- Enter a, b, and c (a can’t be 0).
- Read the discriminant and roots.
Worked examples
- D = 9 − 8 = 1
- x = (3 ± 1) ÷ 2
x = 2 and x = 1.
Measurement guidance
Rearranging first
Move all terms to one side so the equation equals zero before reading a, b, and c.
Frequently asked questions
What if a is zero?
Then it’s a linear equation, not a quadratic.
What does i mean?
i is the imaginary unit, √−1, used for complex roots.