1) 2x + 3 = 15
2x = 15-3
2x = 12
x = 12/2
x = 6
2) 5x = 2
x = 2/5 = 0,4
3) 2x + 5 = 6x -7
2x -6x = -7 -5
-4x = -12
x = -12/-4
x = 3
4) -7x + 3 = 4 + x
-7x -x = 4 -3
-8x = 1
x = -1/8
5) 2(x-5) -3(x-4) = 0
2x -10 -3x + 12 = 0
-x + 2 = 0
-x = -2
x = 2
6) 3(x-2) = 7x -(x+1)
3x -6 = 7x -x -1
3x -7x +x = -1 + 6
-3x = 5
x = -5/3
7) 8(x-2) = 4(2x-4) - 3x
8x -16 = 8x -16 -3x
8x -8x + 3x = -16 + 16
3x = 0
x = 0
Voilà, bonne fin de soirée ;)
