\begin{frame}
  \frametitle{Differentiation Rules: Product Rule}

  \begin{talign}
    h'(x) = \lim_{\Delta x \to 0} \frac{\Delta h}{\Delta x} 
    &&\text{where}&&
    \begin{aligned}
    \Delta h &= h(x+\Delta x) - h(x) \\
    \Delta f &= f(x+\Delta x) - f(x) \\
    \Delta g &= g(x+\Delta x) - g(x)
    \end{aligned}
  \end{talign}
  Then
  \begin{talign}
    \Delta h &= \Delta f\cdot g(x) + f(x) \cdot \Delta g + \Delta f \cdot \Delta g
  \end{talign}\vspace{-2ex}
  \pause
  \begin{center}
    \begin{tikzpicture}[default]
      \coordinate (a) at (0,0);
      \coordinate (b) at (3,2);
      \coordinate (c) at (5,2.7);
      \coordinate (u1) at (0,2);
      \coordinate (u2) at (3,2.7);
      \coordinate (r1) at (3,0);
      \coordinate (r2) at (5,2);
      \draw (a) rectangle (b);
      \draw[fill=cgreen!25] (r1) rectangle (r2);
      \draw[fill=cgreen!25] (u1) rectangle (u2);
      \draw[fill=cred!25] (b) rectangle (c);

      \draw[gray,decorate,decoration={brace,amplitude=5pt,mirror,raise=2pt}] (0,2.7) -- node[left,xshift=-3mm] {$f(x+\Delta x)$} (0,0);      
      \draw[gray,decorate,decoration={brace,amplitude=5pt,mirror,raise=2pt}] (0,0) -- node[below,yshift=-3mm] {$g(x+\Delta x)$} (5,0);      

      \draw[gray,decorate,decoration={brace,amplitude=5pt,mirror,raise=2pt}] (5,0) -- node[right,xshift=3mm] {$f(x)$} (5,2);      
      \draw[gray,decorate,decoration={brace,amplitude=5pt,mirror,raise=2pt}] (5,2) -- node[right,xshift=3mm] {$\Delta f$} (5,2.7);      

      \draw[gray,decorate,decoration={brace,amplitude=5pt,mirror,raise=2pt}] (3,2.7) -- node[above,yshift=3mm] {$g(x)$} (0,2.7);      
      \draw[gray,decorate,decoration={brace,amplitude=5pt,mirror,raise=2pt}] (5,2.7) -- node[above,yshift=3mm] {$\Delta g$} (3,2.7);      

      \node at ($(b)!.5!(c)$) {$\Delta f\Delta g$};
      \node at ($(u1)!.5!(u2)$) {$\Delta f \cdot g(x)$};
      \node at ($(r1)!.5!(r2)$) {$\Delta g \cdot f(x)$};
      \node at ($(a)!.5!(b)$) {$\underbrace{f(x) \cdot g(x)}_{h(x)}$};
    \end{tikzpicture}
  \end{center}
  \vspace{10cm}
\end{frame}