bonsoir
le 1 est juste
le 2 aussi
x + 1 = 2 x- 1
x- 2 x = - 1 - 1
- x = - 2
x = 2
2 ( x - 1 ) - 4 ( 2 - x ) = 3 x - 7
2 x - 2 - 8 + 4 x = 3 x - 7
6 x - 3 x = - 7 + 10
3 x = 3
x = 1
x² + x + 1 = ( x + 1 ) ( x - 1 )
x² + x + 1 = x² - 1
x² - x² + x = - 1 - 1
x = - 2