bjr

ex 43

5x + 7 = 2x - 2

but du jeu : les x à gauche et les constantes à droite

explication complète :

5x + 7 - 7 = 2x - 2 - 7

5x = 2x - 9

5x - 2x = 2x - 2x - 9

3x = -9

3x/3 = -9/3

x = - 3

3x + 2 = x - 10

3x + 2 - 2 = x - 10 - 2

3x = x - 12

3x - x = x - x - 12

2x = -12

2x/2 = -12/2

x = - 6

44

2x - 5 = 5x + 1

2x - 5x = 1 + 5

-3x = 6

x = -2

et

3 - 7x = 3x + 2

-7x - 3x = 2 - 3

- 10x = -1

x = 1/10