a,ƯCLN(48,120)=24
BCNN(48,120)=240
b,ƯCLN(54,90) =18
BCNN(54,90) =270
\(48=2^4.3\)
\(120=2^3.3.5\)
\(UCLN(48;120)=2^3.3=24\)
\(BCNN(48;120)=2^4.3.5=240\)
\(54=2.3^3\)
\(90=2.3^2.5\)
\(UCLN(54;90)=2.3^2=18\)
\(BCNN(54;90)=2.3^3.5=270\)