Réponses

2014-03-11T16:14:35+01:00


Exercice 47:

a) 7x = 3x + 18

7x - 3x = 18

4x = 18

x = 18/4

x = 4,5


b) 3x + 2 = 2x + 7

3x - 2x = 7 - 2

1x = 5

x = 5


c) 3x - 6 = 9x

3x - 9x = +6

-6x = 6

x = 6/(-6)

x = -1


d) 4x + 5 = 18

4x = 18 - 5

4x = 13

x = 13/4

x = 3,25


e) 18x = 21x - 15

18x - 21x = -15

-3x = -15

x = -15 / (-3)

x = 5


f) 8 = 15 - x

x = 15 - 8

x = 7