Réponses

2014-06-04T16:34:29+02:00
a)
12 + x = 5 - 13x
x + 13x = 5 - 12
14x = - 7
x = - 7/14
x = - 1/7

b)
3x + 7 (8 - x) + 4 = 60 + x
3x + 56 - 7x + 4 = 60 + x
3x - 7x - x = 60 - 56 - 4
- 5x = 60 - 60
- 5x = 0
x = - 0/5
x = 0

c)
7x - 8 = 3x + 2
7x - 3x = 2 + 8
4x = 10
x = 10/4
x = 2,5

d)
5 (x - 2) + 2 (1 - 3x) = 7x + 12
5x - 10 + 2 - 6x = 7x + 12
5x - 6x - 7x = 12 + 10 - 2
- 8x = 20
x = - 20/8
x = - 2,5