, ).
Think about how this compares with your answer to #1, and what the graphs
of these three functions (f itself and the two approximations) look like.
2. Find a quadratic approximation for f(x,y) = cos x cos y near the
point (, ).
Think about how this compares with your answer to #1, and what the graphs
of these three functions (f itself and the two approximations) look like.
3. Find a quadratic approximation for g(x,y) = 
near (0,0).
4. Use your approximation from #3 to estimate the value of g(0.1,0.1).
Compare with the actual value of g(0.1,0.1).
5. Try to find a quadratic approximation for g(x,y) =
near (1,0). What goes wrong?
6. Find a quadratic approximation for h(x,y) = xey near (1,1).
7. Use your approximation from #6 to estimate h(1.1,0.9). Compare with
the actual value of h(1.1,0.9).
8. Find a quadratic approximation to the plane p(x,y) = ax + by + c
near the origin. Think about it.