\begin{Bmatrix}
		1&2\\
		4&5
	\end{Bmatrix}

结果：$\left\{\begin{array}{cc}1& 2\\ 4& 5\end{array}\right\}$

\begin{matrix}
	   1&2\\
	   4&5
	   \end{matrix}

结果：$\begin{array}{cc}1& 2\\ 4& 5\end{array}$

\begin{bmatrix}
	      1&2\\
	      4&5
	      \end{bmatrix}

结果：$\left[\begin{array}{cc}1& 2\\ 4& 5\end{array}\right]$

  \begin{pmatrix}
	         1&2\\
	         4&5
	         \end{pmatrix}

结果：$\left(\begin{array}{cc}1& 2\\ 4& 5\end{array}\right)$

  \begin{Vmatrix}
	            1&2\\
	            4&5
	            \end{Vmatrix}

结果：$\Vert \begin{array}{cc}1& 2\\ 4& 5\end{array}\Vert$

 \begin{vmatrix}
	           1&2\\
	           4&5
	           \end{vmatrix}

结果：$\left|\begin{array}{cc}1& 2\\ 4& 5\end{array}\right|$