Bonsoir,
a. 3x + 5 < 8
3x< 8-5
3x < 3
3x : 3 < 3 : 3
x < 1
S=]-infini;1[
b. 15 < 7 - 2x
15 - 7 < 2x
8 < 2x
8 : 2 < 2x : 2
4 < x
S=]4;infini[
c. -3 + 5x < 7x
5x - 7x < 3
-2x < 3
-2x : -2 > 3 : 2
x > 3/2
S=] 3/2; infini[
d. 4x - 8 > 10x + 3
4x - 10x > 3 +8
-6x > 11
-6x : -6 < 11 : -6
x < -11/6
S=]-11/6;infini[
e. -x - 6 > 0
-x > 0 + 6
-x > 6
-1x : -1 < 6 : -1
x < -6
S=]-6;infini[
f. 4 < -6x
4 : -6 > -6x : -6
-4/6 > x
S=] -4/6;infini[