Matrices
$$ \begin{matrix} a &b \\ c &d \end{matrix} $$$$
\begin{matrix}
a &b \\
c &d
\end{matrix}
$$
$$
\begin{pmatrix}
a &b \\
c &d
\end{pmatrix}
$$$$
\begin{pmatrix}
a &b \\
c &d
\end{pmatrix}
$$
$$
\begin{bmatrix}
a &b \\
c &d
\end{bmatrix}
$$$$
\begin{bmatrix}
a &b \\
c &d
\end{bmatrix}
$$
$$
\begin{vmatrix}
a &b \\
c &d
\end{vmatrix}
$$$$
\begin{vmatrix}
a &b \\
c &d
\end{vmatrix}
$$
$$
\begin{Vmatrix}
a &b \\
c &d
\end{Vmatrix}
$$$$
\begin{Vmatrix}
a &b \\
c &d
\end{Vmatrix}
$$