This looks so simple but .. I can't prove or disprove this.
[Definition (irreducible element of ring)] ☞ Let $R$ is commutative ring with unity $1$. $u$ is irreducible elements in $R$ iff $u$ is non-zero, non-unit, and $u = ab$ imply $a$ is unit or $b$ is unit of $R$
please help me.
I already know $u$ is irreducible elements in $Z_n$ ring iff $u$ associate $p$( that is, $u=pc$ , $c$ is unit in $Z_n$) , where $p$ is prime and $ p^2 $divide $ n$.
but I can't prove this or take counterexample .