a factoriser x²+2x-15 merci

Bonjour

Factoriser x² + 2x - 15

On calcule D
D = b² - 4ac
D = 2² - (4 x 1 x (-15))
D = 4 + 60 = 64 
V(64) = 8


Calculons x1 et x2
x1 =( -2 + 8) / 2 = 3
x2 = (-2 - 8) / 2  = -5

Factorisons
x² + 2x - 15 = (x-3)(x+5)