کد: [انتخاب]
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[\begin{bmatrix}s_1\\s_2 \end{bmatrix} \sim \left(\begin{matrix} \beta_1\\ \beta_2 \end{matrix} \begin{bmatrix}\tau_{11}^2 & \\ \tau_{21}^2 & \tau_{22}^2 \end{bmatrix} \right)\]
\end{document}