Réponse :

3.

a) -4x + 3

b) 3x - 7

c) -2x² + 3x - 5

d) x² + 3x - 1

4.

A) 8x + 3 - (6x + 2) = 8x + 3 - 6x - 2 = 2x + 1

B) (9x + 5) + (-2x + 3) = 9x + 5 - 2x + 3 = 7x + 8

C) (4x - 9) - (2x - 7) = 4x - 9 - 2x + 7 = 2x - 2

D) (9x + 5) -2x + 3 = 9x + 5 - 2x + 3 = 7x + 8

E) (4x - 9) - 2x + 7 = 4x - 9 - 2x + 7 = 2x - 2

H) 8x + 3 - 6x - 2 = 2x + 1

(A-H), (B-D), (C-E)

5.

K = 5x - (2x - 3) = 5x - 2x + 3 = 3x + 3 = 3 (x + 1)

L = 3x² - (4x² - x + 5) = 3x² - 4x² + x - 5 = -x² + x - 5

M = 4 + 6x - (-2x + 7) = 4 + 6x + 2x - 7 = 8x - 3

N = - 5x - (-5x² + x - 1) = -5x + 5x² - x + 1 = 5x² + 4x + 1

O = (6a + 8) - (4a + 2) = 6a + 8 - 4a - 2 = 2a + 6 = 2 ( a + 3)

P = (7b -2) + (3b - 5) = 7b - 2 + 3b - 5 = 10b - 7

Explications étape par étape