a) (x - 1)(x + 2) + 4(x - 1) = 0 b) (x - 1) au carrer – 3(x - 1) = 0 c) 4x – 1 - 3(2x + 1) = 0. d) 3x – x au carrer = 0 e) (x +

Réponse :

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Factoriser :

A) (x - 1)(x + 2) + 4(x - 1) = 0

(x - 1)(x + 2 + 4) = 0

(x - 1)(x + 6) = 0

x - 1 = 0 ou x + 6 = 0

x = 1 ou x = -6

b) (x - 1) au carrer – 3(x - 1) = 0

(x - 1)(x - 1 - 3) = 0

(x - 1)(x - 4) = 0

x - 1 = 0 ou x - 4 = 0

x = 1 ou x = 4

c) 4x – 1 - 3(2x + 1) = 0. (On ne peut pas factoriser)

4x - 1 - 6x - 3 = 0

-2x - 4 = 0

2x = -4

x = -4/2

x = -2

d) 3x – x au carrer = 0

x(3 - x) = 0

x = 0 ou 3 - x = 0

x = 0 ou x = 3

e) (x + 2)(x – 3) = 6 - 2x

(x + 2)(x - 3) = 2(3 - x)

(x + 2)(x - 3) - 2(3 - x) = 0

(x + 2)(x - 3) + 2(x - 3) = 0

(x - 3)(x + 2 + 2) = 0

(x - 3)(x + 4) = 0

x - 3 = 0 ou x + 4 = 0

x = 3 ou x = -4