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Solve ax² + bx + c = 0 and see the roots, including complex roots.
How the calculation works
The discriminant (b² − 4ac) tells you the type of roots: positive gives two real roots, zero gives one repeated root, and negative gives two complex roots.
Formula used
x = (−b ± √(b² − 4ac)) ÷ (2a)
Example
For x² − 5x + 6 = 0 (a = 1, b = −5, c = 6) the discriminant is 1 and the roots are 3 and 2.
Frequently asked questions
Why can’t a be zero?
If a is zero the equation is linear, not quadratic.
What are complex roots?
Roots that include the imaginary unit i, shown when the discriminant is negative.
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Results are estimates for general information only and are not professional financial, medical or legal advice.