![错误显示如下](https://linux22.com/image/407222/%E9%94%99%E8%AF%AF%E6%98%BE%E7%A4%BA%E5%A6%82%E4%B8%8B.png)
\documentclass{article}
\input{tcilatex}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsmath}
\begin{lemma}
The Binet formulas for these sequences are%
\begin{eqnarray}
P_{k,n}(x) &=&\frac{\alpha ^{n}(x)-\beta ^{n}(x)}{\alpha (x)-\beta (x)}, \TCItag{2.6} \\
Q_{k,n}(x) &=&\alpha ^{n}(x)+\beta ^{n}(x), \TCItag{2.7} \\
q_{k,n}(x) &=&\frac{\alpha ^{n}(x)+\beta ^{n}(x)}{2}, \TCItag{2.9}
\end{eqnarray}%
\end{lemma}
错误显示如下
Undefined control sequence.
l.194 ...a ^{n}(x)}{\alpha (x)-\beta (x)}, \TCItag {2.6} \\
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