Posted by haifeng on 2025-10-12 18:06:07 last update 2025-10-12 18:06:51 | Answers (1)
设
\[
A_n=\begin{pmatrix}
a & b & b & \cdots & b\\
c & a & b & \cdots & b\\
c & c & a & \cdots & b\\
\vdots & \vdots & \vdots &\ddots & \vdots\\
c & c & c & \cdots & a
\end{pmatrix}
\]