9. LaTeX技巧644：公式上的斜线箭头

在公式上cancel是不错的想法，有时，我们需要下面的方式该如何实现：

选自：http://tex.stackexchange.com/questions/31323/cross-out-with-arrow-as-in-goes-to-zero

样例代码：

\documentclass{article}
\usepackage{cancel}
\begin{document}

\[
\cancelto{0}{x}
\]
\end{document}

样例代码二：

\documentclass{beamer}

\usepackage{mathtools,cancel}

\renewcommand{\CancelColor}{\color{red}} %change cancel color to red

\makeatletter
\let\my@cancelto\cancelto %copy over the original cancelto command
\newcommand<>{\cancelto}[2]{\alt#3{\my@cancelto{#1}{#2}}{\mathrlap{#2}\phantom{\my@cancelto{#1}{#2}}}}
% redefine the cancelto command, using \phantom to assure that the
% result doesn't wiggle up and down with and without the arrow
\makeatother

\begin{document}
\begin{frame}

\scalebox{5}{
$\cancelto<2>{0}{x}(1-x)=0$
} %use the new cancelto command

\end{frame}
\end{document}