\begin{frame}
  \frametitle{Exponential Population Growth}

  \begin{exampleblock}{}
    Let $y$ be the size of a population.
  \end{exampleblock}
  \pause\medskip
  
  Instead of saying `the growth rate is proportional to the size'
  \begin{talign}
    y' = ky
  \end{talign}
  \pause
  we can equivalently say that the \emph{relative growth rate}
  \begin{talign}
    \frac{y'}{y} = k &&\mpause[1]{\text{ or equivalently }}&&\mpause[1]{\frac{1}{y}\frac{dy}{dt} = k}
  \end{talign}
  is constant.
  \pause\pause\bigskip
  
  Then the solution is of the form
  \begin{talign}
    y = Ce^{kt}
  \end{talign}  
\end{frame}