\begin{frame}
  \frametitle{Optimization}

  The argument we have used on the last slide is the following:
  \bigskip
  \begin{block}{First Derivative Test for Absolute Extreme Values}
    Let $f$ be continuous, defined on an open or closed interval.\\
    Let $c$ be a critical number of $f$.
    \begin{itemize}
      \medskip
      \item If $f'(x) > 0$ for all $x < c$, and $f'(x) < 0$ for all $x > c$,\\
        then $f(c)$ is the absolute maximum of $f$.
      \medskip
      \item If $f'(x) < 0$ for all $x < c$, and $f'(x) > 0$ for all $x > c$,\\
        then $f(c)$ is the absolute minimum of $f$.
    \end{itemize}
  \end{block}
\end{frame}