Bonjour,
1) -5x - 6 -2 = -5x - 7
-5x +5x = -7 +6+2
impossible:
0 = +1
2) -x - 3 - x = -4x + 2
-x+4x -x = 2 +3
2x = 5
x= 5/2 = 2,5
3) -7 - 4x = -5x - 1
-4x+5x = -1 +8
x = 7
4) -3 ( 4x - 5 ) = 6x
-12x +15 = 6x
15 = 6x +12x
15 = 18x
x= 15/18
x = 5/6
5) - 2x - ( 4x + 7 ) = - 3x + ( 7x + 5 )
-2x -4x -7 = -3x +7x +5
-7 -5 = -3x +7x+2x +4x
-12 = 10x
x = - 12/10
x = - 6/5
