How it is calculated
The discriminant is D = b² − 4ac. If D > 0 there are two roots, if D = 0 there is one, and if D < 0 there are no real roots. A root is (−b ± √D) / 2a.
x = (−b ± √D) / 2a
Where the numbers come from
- Coefficient a
- Coefficient b
- Coefficient c
Example
x² − 3x + 2 = 0. Discriminant 9 − 8 = 1, roots 2 and 1.
Questions
How do I write the equation x² − 3x + 2?
a = 1, b = −3, c = 2. The minus belongs to the coefficient.
What about complex roots?
The calculator reports that there are no real roots, and it shows the negative discriminant.
Does root order matter?
No. The root with a plus in front of the square root of the discriminant is shown first.