I am having problems showing $\displaystyle X\subseteq ann(ann(X))$. I don't understand how I would start this problem and don't understand what the annihilator of an annihilator would be.
I am having problems showing $\displaystyle X\subseteq ann(ann(X))$. I don't understand how I would start this problem and don't understand what the annihilator of an annihilator would be.
Thanks for the help!
Let $\displaystyle x\in X\Longrightarrow nx=0\,\,\,\forall\,n\in Ann(X)\Longrightarrow\,x$ annihilates every $\displaystyle n\in Ann(X)\Longrightarrow\,x\in\,Ann(Ann(X))$