\(x\in\left(A\B\right)\cup\left(A\cap B\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x\in A\\x\notin B\end{matrix}\right.\\\left\{{}\begin{matrix}x\in A\\x\in B\end{matrix}\right.\end{matrix}\right.\Leftrightarrow x\in A\)(ĐPCM)