1) 3 x - 2.5 = - 8 + 2.5 x
3 x - 2.5 x = - 8 + 2.5
0.5 x = - 5.5
x = - 11
2) x/3 + 3/4 = x - 1
4 x /12 + 9/12 = 12 x - 12
4 x - 12 x = - 12 - 9
- 8 x = - 21
x = 21/8
3) x² + 25 = 0
( x +5) ( x + 5) = 0
x + 5 = 0 et x = - 5
4) 13 x + 8 ≤ 10 x - 2
13 x - 10 x ≤ - 2 - 8
3 x ≤ - 10
x ≤ - 10/3
5) 4 x - 0.5 ≥ 2 x/3 + 1
12 x - 1.5 ≥ 2 x + 3
12 x - 2 x ≥ 3 + 1.5
10 x ≥ 4.5
x ≥ 4.5/10
x ≥ 45/100 ou 9/20
6) x+ 2 < 0
x < - 2