# Math Help - need a help

1. ## need a help

Let H be a subgroup of G then show that $H \capC_G(H)=Z(G)$

2. Can you post that again? It gives "LaTeX Error: Syntax error".

3. ## need help

Let H be a subgroup of G, then $H\cap C_G(H)=Z(H)$.

4. Originally Posted by dimuk
Let H be a subgroup of G, then $H\cap C_G(H)=Z(H)$.
Just do it by definition. $Z(H)$ means all $x\in H$ so that $x$ commutes with every element in $G$. But that is the same thing as $x\in H$ and $x\in C_G(H)$.