Répondre :
g(x) =x^3 +5x²-12x+6
a) g(1) = 1+5-12+6 = 0
b) g(x) = (x-1)(ax²+bx+c) = ax^3 + (b-a)x² + (c-b)x - c
donc a = 1 ; (b-1) = 5 soit b = 6 ; c - 6 = 12 soit c = -6
g(x) = (x-1)(x²+6x-6)
a) g(1) = 1+5-12+6 = 0
b) g(x) = (x-1)(ax²+bx+c) = ax^3 + (b-a)x² + (c-b)x - c
donc a = 1 ; (b-1) = 5 soit b = 6 ; c - 6 = 12 soit c = -6
g(x) = (x-1)(x²+6x-6)