## Thinking Mathematically (6th Edition)

If $A\subseteq B$, then $A\cap B = B$ This is false. $B$ is a superset of $A$ and can have elements that aren't in $A$. Those elements can't be in $A\cap B$, which means $A\cap B \neq B$. It should say: If $A\subseteq B$, then $A\cap B = A$