Bonjour
3y - 2 = 5y
3y - 5y = 2
- 2y = 2
y = - 2/2 = - 1
y² = 6y
y² - 6y = 0
y (y - 6) = 0
y = 0 ou y - 6 = 0
y = 6
2y = y/5 + 9
2y - y/5 = 9
10y/5 - y/5 = 9
9y/5 = 45/5
9y = 45
y = 45/9
y = 5
4 (y + 1) = y - 2
4y + 4 = y - 2
4y - y = - 2 - 4
3y = - 6
y = - 6/3 = - 2.