B(30)={0;30;60;90;120;...}
B(100)={0;100;200;300;...}
\(30=2.3.5\)
\(\Rightarrow B\left(30\right)=\left\{0;30;60;...\right\}\)
\(100=2^2.5^2\)
\(\Rightarrow B\left(100\right)=\left\{0;100;200;...\right\}\)
\(\Rightarrow BCNN\left(30;100\right)=2^2.3.5^2=300\)
\(\Rightarrow BC\left(30;100\right)=B\left(300\right)=\left\{0;300;600;...\right\}\)
Chúc bạn học tốt!