$\text{a. 30 = 2 . 3 . 5}$
$\text{280 = 2³ . 5 . 7}$
$\text{BCNN (30; 280) = 840}$
$\text{BC (30; 80) = B (840) = {0; 840; 1680;...}}$
$\text{b. 24 = 2³ . 3}$
$\text{40 = 2³ . 5}$
$\text{168 = 2³ . 3 . 7}$
$\text{BCNN (24; 40; 168) = 840}$
$\text{BC (24; 40; 168) = B (840) = {0; 840; 1680;...}}$
$\text{#nocopy}$
$\text{@huyen}$