Svp j'ai vraiment besoin d'aide pour l'exercice, le 9 svp merci !!

1) 15x-5 =0
15x =5
x = 5/15 = 1/3

3-4x = 0
-4x =-3
x = 3/4

S{1/3;3/4}

2) 17-3x =0
-3x =-17
x =17/3

12x =0
x = 0

S{17/3;0}

3) 12x=4 = 0
12x= -4
x = -4/12  =-1/3

13-26x = 0
-26x =-13
x =13/26 = 1/2

-5x =0
x = 0

S{-1/3; 1/2;0}