iables that are inputs to the function. If the function is $f(x,y)$, then the derivative
        is $Df(x,y) = \begin{bmatrix}\frac{\partial f}{\partial
        x}&amp;\frac{\partial f}{\partial y}\end{bmatrix}.$ If the
        function is $V(x,y,z)$, then the derivative is $DV(x,y,z) =
        \begin{bmatrix}\frac{\partial V}{\partial
        x}&amp;\frac{\partial V}{\partial y}&amp;\frac{\partial
        V}{\partial z}\end{bmatrix}.$
      </li>
    </ul>
  </div>
                    <p>It's time to pract