\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}
\documentclass{article} \usepackage{amsmath} \begin{document} \[ M= \begin{bmatrix} 1 & 2 & 3 & 4 & 5 \\ 3 & 4 & 5 & 6 & 7 \end{bmatrix} \] \end{document}