如何正确编写分支函数

Question

我尝试编写如下分支函数：

 $Pr{NC|\alpha}=$ \[ \left\{
\begin{array}{ll}
      (1-p)^{n-1}(1-p+p(\alpha + \beta)^{2})^{n-1} & 0\leq x \leq \beta \\
      (1-p)^{n-1}(1-p+4p\alpha\beta)^{n-1} & \beta\leq x\leq \beta-1\\
      (1-p)^{n-1} (1-p(\alpha - \beta)^{2})^{n-1} & 1-\beta\leq x\leq 1 \\

\end{array} 
\right. \]

但是Pr{NC|\alpha}=出现了一个孤独的函数，而第二行上，我怎样才能把它们放在同一行？

Answer 1

概率的括号版本并不明显。建议（在\[...中使用一个 displaymath \]）：

\documentclass{article}

\begin{document} 

\[ 
\Pr\{\mathrm{NC}|\alpha\}= \left\{
\begin{array}{ll}
      (1-p)^{n-1}(1-p+p(\alpha + \beta)^{2})^{n-1} & 0\leq x \leq \beta \\
      (1-p)^{n-1}(1-p+4p\alpha\beta)^{n-1} & \beta\leq x\leq \beta-1\\
      (1-p)^{n-1} (1-p(\alpha - \beta)^{2})^{n-1} & 1-\beta\leq x\leq 1 \\
\end{array} 
\right. 
\]
\end{document}