3x + 7 = (9 + x) + 2x3x + 7 = 9 + x + 2x3x + 7 = 9 + 3x7 = 9This equation is inconsistent and has no solution.
5x - 1 = 4(x + 2) - (9 - x)5x - 1 = 4x + 8 - 9 + x5x - 1 = 5x - 1This equation is an identity and has infinitely many solutions.
x + 1 = x - 1x + 1 = x - 11 = -1This equation is inconsistent and has no solution.
3x + 7 = (9 + x) + 2x
3x + 7 = 9 + x + 2x
3x + 7 = 9 + 3x
7 = 9
This equation is inconsistent and has no solution.
5x - 1 = 4(x + 2) - (9 - x)
5x - 1 = 4x + 8 - 9 + x
5x - 1 = 5x - 1
This equation is an identity and has infinitely many solutions.
x + 1 = x - 1
x + 1 = x - 1
1 = -1
This equation is inconsistent and has no solution.