The quadratic formula solves any equation of the form ax² + bx + c = 0.
Quadratic formula
x = (−b ± √(b² − 4ac)) / 2a
Try it
x² − 5x + 6 = 0
a=1, b=−5, c=6. x = (5 ± √(25−24))/2 = (5±1)/2 = 3 or 2.
The discriminant b² − 4ac tells you how many real roots: positive = 2, zero = 1, negative = 0.