Pertidaksamaan kuadrat X2-5X+6<0

X² – 5x + 6 = 0
(x – 3)(x – 2) = 0

x1 = 3 dan x2 = 2

x1 – 3 = 3 – 3 = 0
x2 – 3 = 2 – 3 = -1

persamaan yang barunya :
(x – 0)(x + 1) = 0
x(x + 1) = 0
x² + x = 0