Bonjour,
développer puis factoriser
= -5(x+3)(x-1)+9-x^2
= -5(x^2 - x + 3x - 3) + 9 - x^2
= -5x^2 - 10x + 15 + 9 - x^2
= -6x^2 - 10x + 24
Factoriser :
= -5(x + 3)(x - 1) + 3^2 - x^2
= -5(x + 3)(x - 1) + (3 - x)(3 + x)
= (x + 3)[-5(x - 1) + 3 - x]
= (x + 3)(-5x + 5 + 3 - x)
= (x + 3)(-6x + 8)
= 2(x + 3)(-3x + 4)
