bonjour
a) x + ( 2 x -3 ) + ( x - 7 ) = 12
x + 2 x - 3 + x - 7 = 12
4 x - 10 = 12
4 x = 12 + 10
4 x = 22
x = 22/4 = 11 /2
b ) 20 x - 28 = 32
20 x = 32 + 28
20 x = 60
x = 3
c ) 6 x - 3 - 5 x = 3 x - 1
x - 3 x = - 1 + 3
- 2 x = 2
x = - 1
d) 2 x - 6 + 3 x - 3 = 2 x - 3
5 x - 2 x = - 3 + 6 + 3
3 x = 6
x = 2
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e ) 5 x - 6 x + 2 = 3 x + 9 - 8 x - 12
- x - 3 x + 8 x = - 12 + 9 - 2
4 x = - 5
x = - 5/4
bonne journée
