G/s a<b
ƯCLN(a,b)=6\(\Rightarrow\)a=6.m
b=6.n
ƯCLN(m,n)=1
a.b=216
\(\Rightarrow\)6.m.6.n=216
\(\Rightarrow\)36.m.n=216
\(\Rightarrow\)m.n=216:36=6
Ta có:a<b
a=6.m
b=6.n
ƯCLN(m,n)=1
m<n(Vì a<b)
\(\Rightarrow\) Ta có bảng:
m 1 2
n 6 3
a 6 12
b 36 18
Vậy (a,b)=(6,36)=(12,18)