Thread: GCD

why do we say that if a,b,c are pairwise coprime then gcd(a,b,c)lcm(a,b,c)=abc

when do we enforce that they are pairwise coprime instead of gcd(a,b,c)=1?

Pairwise coprime means that every pair of two integers is coprime. For example, {12,36,49} and {12,35,47} both have GCD equal to 1, but {12,36,49} is not pairwise coprime.