计算$\left|\begin{array}{cccccc}
x & a_1 & a_2 & \cdots & a_{n-1} & 1 \\
a_1 & x & a_2 & \cdots & a_{n-1} & 1 \\
a_1 & a_2 & x & \cdots & a_{n-1} & 1 \\
\vdots & \vdots & \vdots & & \vdots & \vdots \\
a_1 & a_2 & a_3 & \cdots & x & 1 \\
a_1 & a_2 & a_3 & \cdots & a_n & 1
\end{array}\right|$