Bonjour,
a) 10+3x= 16
3x= 16-10
x= 6/3
x= 2 S= { 2 }
b) 21x-5= 3x+2
21x-3x= 2+5
18x= 7
x= 7/18 S= { 7/18 }
c) -7x+2x= 3
-5x= 3
x= -3/5
d) 15-2x= 1-x
-2x+x= 1-15
-x= -14
x= 14
e) 2x+2 < 18
2x < 18-2
x < 16/2
x < 8
S= ] -∞; -8 [
f) 4x-5 ≤ -23+2x
4x-2x ≤ -23+5
2x ≤ -18
x ≤ -9
S= ] -∞; -9 ]
g) 2-x > 3x+26
-x-3x > 26-2
-4x > 24
x < -24/4
x < -6
S= ] -∞; -6 [
h) 3-6x ≥ 126-3x
-6x+3x ≥ 126-3
-3x ≥ 123
x ≤ -123/3
x ≤ -41
S= ] -∞; -41 ]