Sagot :
Alors 1ere équation :
4x + 7 = 3x - 9
4x = 3x -16
1x = -16
x = -16
2eme équation
5x - 7 = 3x - 9
5x = 3x -2
2x = -2
1x = -1
x=-1
4x + 7 = 3x - 9
4x = 3x -16
1x = -16
x = -16
2eme équation
5x - 7 = 3x - 9
5x = 3x -2
2x = -2
1x = -1
x=-1