\begin{frame}
  \frametitle{L'Hospital's Rule}

  \begin{block}{}
  L'Hospital's Rule is valid for one-sided limits and limits at infinity:
  \begin{talign}
    \lim_{x\to a^-} \frac{f(x)}{g(x)} &&
    \lim_{x\to a^+} \frac{f(x)}{g(x)} &&
    \lim_{x\to \infty} \frac{f(x)}{g(x)} &&
    \lim_{x\to -\infty} \frac{f(x)}{g(x)}
  \end{talign}
  \end{block}

%   \begin{proof}
%     For the special case $f(a) = g(a) = 0$ and $g'(a) \ne 0$, the proof of L'Hospital's Rule is easy:
%     \begin{talign}
%       \lim_{x\to a} \frac{f(x)}{g(x)} 
%       &\mpause[1]{= \lim_{x\to a} \frac{f(x)-f(a)}{g(x)-g(a)}  }
%       \mpause[2]{= \lim_{x\to a} \frac{\frac{f(x)-f(a)}{x-a}}{\frac{g(x)-g(a)}{x-a}}  }\\
%       &\mpause[3]{= \frac{\lim_{x\to a} \frac{f(x)-f(a)}{x-a}}{\lim_{x\to a} \frac{g(x)-g(a)}{x-a}}  }
%     \end{talign}
%   \end{proof}  
\end{frame}