n
          class.
        </div>$$ z-4=\begin{bmatrix}-4 &amp; -2
        \end{bmatrix}\begin{bmatrix}x-2\\y-1\end{bmatrix} \quad
        \text{or}\quad z-4=-4(x-2)-2(y-1).$$ [Hint: What does
        differential notation tell us?]
      </li>
    </ol>
  </div>
    
    <p>Look back at the previous two problems. The first semester
  calculus tangent line equation, with differential notation,
  generalized immediately to the tangent plane equation for
  functions of the form $z=f(x,y)$. We just used the di