答案1
这是一个手动的方法
\documentclass[a4paper]{memoir}
\usepackage[T1]{fontenc}
\usepackage{amsmath,amssymb}
\usepackage{fix-cm}
\begin{document}
\[
BP=\left(
\begin{array}{@{} c|c @{}}
\begin{matrix}
\quad\text{\fontsize{10mmm}{10mm}\selectfont$0$}\quad
\end{matrix}
&
\begin{matrix}
b_1\\\vdots\\b_{n-1}
\end{matrix}
\\
\hline
& 0
\end{array}
\right)
\]
\end{document}
答案2
与。{pNiceArray}
nicematrix
\documentclass[a4paper,12pt]{article}
\usepackage{geometry}
\usepackage{nicematrix}
\begin{document}
\[
BP =
\begin{pNiceArray}{w{c}{15mm}|c}[margin=1pt]
\Block{3-1}<\Large>{0} & b_1 \\
& \Vdots \\
& b_{n-1} \\
\Hline
& 0
\end{pNiceArray}
\begin{pNiceArray}{w{c}{15mm}|c}[margin=1pt]
\Block{3-1}<\Large>{Q} & 0 \\
& \Vdots \\
& 0 \\
\Hline
& 1
\end{pNiceArray}
\]
\end{document}