Trl:
\(x⋮12;25\Rightarrow x\in BCNN\left(12;25\right);x\inℕ^∗\)
Ta có :
\(12=2^2.3\)
\(25=5^2\)
\(\Rightarrow BCNN\left(12;25\right)=2^2.3.5^2=300\)
\(\Rightarrow BC\left(12;25\right)=B\left(300\right)=\left\{0;300;600;...\right\}\)
Vậy x = 300
Mà 0 < x < 300 \(\Rightarrow x\in\left\{\varnothing\right\}\)