[tex]Deci,~(a;b)=12 \Rightarrow \\ a=12x \\ b=12y,~ unde ~ (x;y)=1.[/tex]
[tex]Stim~ca~[a;b]=12*x*y~\Rightarrow~12*x*y=72\Rightarrow~x*y=6.[/tex]
[tex]Avem~cazurile: \\ x=1, ~ y=6 \Rightarrow \boxed{a=12;~b=72}(si~invers)\\ x=2,~y=3\Rightarrow \boxed{a=24;~b=48}(si~invers).[/tex]