Réponse :
Bonjour
Explications étape par étape
1) factoriser A
A = (x-3)(x+3)-2(x-3)
A = (x-3)(x+3-2)
A = (x-3)(x+1)
2) développer A
A = (x-3)(x+1)
A = x^2 + x - 3x -3
A = x^2 -2x - 3
3)
a) x = - 1
A = x^2 -2x - 3
A = (-1)^2 - 2*(-1) - 3
A = 1 + 2 - 3
A = 0
b) x = 0
A = (x-3)(x+1)
A = (0-3)(0+1)
A = -3 * 1
A = -3
