Algebra 1 · Quadratic Functions
Quadratic Formula
Algebra 1 · Quadratic Functions
Definition
The quadratic formula x = (−b ± √(b2 − 4ac)) / (2a) solves any quadratic equation ax2 + bx + c = 0.
Examples
- For x2 − 5x + 6 = 0, x = 2 or x = 3.
- It works even when a quadratic will not factor.
Key rule
Substitute a, b, and c into the formula to find the roots.
Memory hook
Quadratic formula solves them all: −b, plus or minus the root, over 2a.