What is the matrix LaTeX: E23(0.5)AE 23 ( 0.5 ) A? code example

Example 1: how to make matrix latex

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\begin{document}
$$
\begin{bmatrix} 
a & b & c \\
c & d & d\\
e & f & g \\
\end{bmatrix}
\quad
$$
\end{document}

Example 2: matrix latex

$\left(\begin{array}{cc} a & b \\ c & d \end{array}\right)$