a) B(4) = {0; 4; 8; 12; 16; 20; 24;... }
B(6) = {0; 6; 12; 18; 24; ... }
BC(4,6) = {0; 12; 24; ...}
b) Ư(15) = {1; 3; 5 ; 15}
Ư(40) = {1; 2; 5; 10; 20; 8; 40}
ƯC(15;40) = {1; 5}
B(4) = {0;4;8;12...}
B(6) = {0;6;12;18...}
BC(4,6) = {0;12;24;36...}
Ư(15) = {1;3;5;15}
Ư(40) = {1;2;4;5;8;10;20;40}
ƯC(15;40) = {1;5}