bjr
bjr
factorisation de ax² + bx + c quand il y a deux racines x1 et x2
a(x - x1)(x - x2)
x² + 8x + 9
Δ = 8² - 4*1*9 = 64 - 36 = 28
√Δ = √28 = √(4*7) = 2√7
x1 = (-8 - 2√7)/2 = -4 -√7
x2 = (-8 + 2√7)/2 = -4 + √7)
x² + 8x + 9 = (x + 4 + √7)(x + 4 - √7)
