答案1
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{gather}
\begin{bmatrix} \Phi_{11} & \Phi_{12} \\ \Phi_{21} & \Phi_{22} \end{bmatrix}
=
\frac{1}{\det(X)}
\begin{bmatrix}
X_{22} Y_{11} - X_{12} Y_{21} &
X_{22} Y_{12} - X_{12} Y_{22} \\
X_{11} Y_{21} - X_{21} Y_{11} &
X_{11} Y_{22} - X_{21} Y_{12}
\end{bmatrix}
\end{gather}
\end{document}
答案2
你可以尝试这个方法:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\begin{bmatrix}
\Phi_{11} & \Phi_{12}\\
\Phi_{21} & \Phi_{22}
\end{bmatrix}
=\frac{1}{\det (X)}
\begin{bmatrix}
X_{22} Y_{11} - X_{12} Y_{21} & X_{22} Y_{12} - X_{12} Y_{22}\\
X_{11} Y_{21} - X_{21} Y_{11} & X_{11} Y_{22} - X_{21} Y_{12}
\end{bmatrix}
\]
\end{document}