先寫下來，之後再補內文
\[
\begin{matrix}
1 & 0 \\
0 & 1
\end{matrix}
\]pmatrix、bmatrix、vmatrix
\[
\begin{array}{c | c}
1 & 0 \\
\hline
0 & 1
\end{array}
\]\[
\left[\!
\begin{array}{c c c | c c c}
1 & 3 & 0 & 1 & 0 & 0 \\
3 & 1 & 9 & 0 & 1 & 0 \\
0 & 9 & 3 & 0 & 0 & 1
\end{array}
\!\right]
\]