Đáp án:
1. Cách 1: Ư(135) = {±1;±3;±5;±9;±15;±27;±45;±135}
Ư(234) = {±1;±2;±3;±6;±9;±13;±18;±26;±39;±78;±117;±234}
ƯC(135,234) = {±1;±3;±9}
ƯCLN(135,234) = 9
Cách 2:
Ta có: 135 = 3³.5
234 = 2 .3³.13
ƯCLN(135,234) = 3² = 9
2. BCNN(8,18,28)
Ta có: 8 = 2³
18 = 2.3²
28 = 2².7
BCNN(8,18,28) = 2³.3².7 = 504
BCNN(9,26)
Ta có: 9 = 3²
26 = 2.13
BCNN(9,26) = 2.3².13 = 234
BCNN(25,75,150)
Ta có: 25 = 5²
75 = 3.5²
150 = 2.3.5²
BCNN(25,75,150) = 2.3.5² = 150
HỌC TỐT NHÉ!