bonsoir merci de m'aider pour ce exercice 1 ) (x + 3 ) = x +6x +9

x + 3 = x + 6x + 9.
x + 3 = 7x + 9.
x + 3 - x = 7x + 9 - x.
3 = 6x + 9.
3 - 9 = 6x + 9 - 9.
-6 = 6x.
-6 / 6 = 6x / 6
-1 = x/

Bonjour

(x + 3) = x + 6x + 9
x - x - 6x = 9 - 3
- 6x = 6
x = - 6/6
x = - 1