Let $G$ be a finite group and $n$ be a given positive integer such that $(ab)^n=a^nb^n , \forall a,b \in G$ and
g.c.d.$\big(|G|,n(n-1)\big)=1$ , then how to prove that $G$ is abelian ? If I can show that
$(ab)^{n(n-1)}=a^{n(n-1)}b^{n(n-1)} , \forall a,b \in G$ then I would be done , so I'm also asking , is this identity true ?