\begin{frame}
  \frametitle{The Substitution Rule: Exercises}
  
  \begin{exampleblock}{}
    \begin{malign}
      \int e^{-x}\, dx &&\text{take $u = \mpause[1]{-x}$}
    \end{malign}
    \pause
  \end{exampleblock}
  \pause

  \begin{exampleblock}{}
    \begin{malign}
      \int x^3(2+x^4)^5\, dx &&\text{take $u = \mpause[1]{2+x^4}$}
    \end{malign}
    \pause
  \end{exampleblock}
  \pause

  \begin{exampleblock}{}
    \begin{malign}
      \int x^2\sqrt{x^3+1}\, dx &&\text{take $u = \mpause[1]{x^3+1}$}
    \end{malign}
    \pause
  \end{exampleblock}
  \pause

  \begin{exampleblock}{}
    \begin{malign}
      \int \frac{1}{(1-6t)^4}\, dt &&\text{take $u = \mpause[1]{1-6t}$}
    \end{malign}
    \pause
  \end{exampleblock}
  \pause

  \begin{exampleblock}{}
    \begin{malign}
      \int \cos^3 \phi \,\sin \phi\, dt &&\text{take $u = \mpause[1]{\cos \phi}$}
    \end{malign}
    \pause
  \end{exampleblock}
  \pause

  \begin{exampleblock}{}
    \begin{malign}
      \int \frac{\sec^2(\frac{1}{x})}{x^2}\, dt &&\text{take $u = \mpause[1]{\frac{1}{x}}$}
    \end{malign}
    \pause
  \end{exampleblock}
\end{frame}