a)

b)

c)

d)

Réponse :

Explications étape par étape

Bonsoir

12x + 15 = 6x + 3

12x - 6x = 3 - 15

6x = -12

x = -12/6

x = -2

5x - 3 = 2x + 4

5x - 2x = 4 + 3

3x = 7

x = 7/3

-7x - 8 = -10x + 4

10x - 7x = 4 + 8

3x = 12

x = 12/3

x = 4

2x + 7 = 9x - 5

7 + 5 = 9x - 2x

12 = 7x

x = 12/7