lculus to find $df/dt$.</div>
      Suppose that $f(x,y)
    = x^2+xy$ and that $x=2t+3$ and $y=3t^2+4$.

    <ol>
      <li>Rewrite the parametric equations $x=2t+3$ and $y=3t^2+4$
      in vector form, so we can apply the chain rule. This means
      you need to create a function $\vec r(t) = (\blank{1in},
      \blank{1in})$.</li>

      <li>Compute the derivatives $Df(x,y)$ and $D\vec r(t)$, and
      then multiply the matrices together to obtain
      $\dfrac{df}{dt}$. How can you make your answer only