 construct a graph in the $yz$ plane of the
      curve $z=f(2,y)=9-2^2-y^2$. Find an equation of the tangent
      line to this curve at $y=1$. Write the equation in the form
      $(z-z_0)=m(y-y_0)$ (find $z_0,m,y_0$). Also, find a direction
      vector $(0,1,?)$ for this line.</li>

      <li>Compute $f_x$ and $f_y$ and then evaluate each at
      $(2,1)$. What does this have to do with the previous two
      parts?</li>

      <li>If the slope of a line $y=mx+b$ is $m$, then we know that
      an incre