Explicație pas cu pas:
x<=5 si x€N =>x€{0,1,2,3,4,5} => A={0,1,2,3,4,5}
y+1<=7 => y<=6 si y€N* => y€{1,2,3,4,5,6}=> B={1,2,3,4,5,6}
5/(z-1)=> z-1€D5 in Z => z-1€{-5,-1,1,5} => z€{-4,0,2,6}
z€N => z€{0,2,6} =>C={0,2,6}
(t+4)/(t+1)€N <=> t+1|t+4 dar t+1|t+1 => t+1|3 (le scadem) =>
t+1€D3 in Z =< t+1€{-3,-1,1,3} => t€{-4,-2,0,2}
t€N => t€{0,2} =>D={0,2}
(2v+7)/(v+1)€N <=> v+1|2n+7 dar v+1|v+1 =>v+1|2v+2
Le scadem : v+1|5 =>v+1€D5 in Z => v+1€{-5,-1,1,5} =>
v€{-6,-2,0,4} si v€N* =>v€{0,4} =>E={0,4}
(2a+7)/(3a+1)€N <=>
3a+1|2a+7 => 3a+1|6a+21
3a+1|3a+1 => 3a+1|6a+2
Le scadem: 3a+1|19 => 3a+1€D19 in Z =>
3a+1€{-19,-1,1,19} =>
3a€{-20,-2,0,18} =>
a€{-20/3,-2/3,0,6}
a€N => a€{0,6} => F={0,6}
