Răspuns:

Divizorii lui 50 sunt 1,2,5,10,25,50.

2x-1=1

2x=1+1

2x=2

x=2/2

x=1€N => A

2x-1=2

2x =2+1

2x =3

x= 3/2 nu apartine N => F

2x-1=5

2x =5+1

2x=6

x=6/2

x=3€N => A

2x-1=10

2x=10+1

2x=11

x=11/2 nu apartine N => F

2x-1=25

2x=25+1

2x=26

x=26/2

x=13€N => A

2x-1=50

2x=50+1

2x=51

x=51/2 nu apartine N => F

S={1; 3; 13}