a) 42 = 2.3.7
58 = 2.29
ƯCLN(42; 58) = 2
ƯC(42; 58) = Ư(2) = {1; 2}
b) 90 = 2.3².5
150 = 2.3.5²
ƯCLN(90; 150) = 2.3.5 = 30
ƯC(90; 150) = Ư(30) = {1; 2; 3; 5; 6; 10; 15; 30}
c) 154 = 2.7.11
13 = 13
ƯCLN(154; 13) = 1
ƯC(154; 13) = Ư(1) = 1
d) 24 = 2³.3
84 = 2².3.7
180 = 2².3².5
ƯCLN(24; 84; 180) = 2².3 = 12
ƯC(24; 84; 180) = Ư(12) = {1; 2; 3; 4; 6; 12)