Use the level curves in the figure to predict the location of the critical points of f and whether f has a saddle point or a local maximum or minimum at each critical point. Explain your reasoning. Then use the Second Derivatives Test to confirm your predictions.

f (x, y) = 4 + x³ + y³ - 3xy

y 3.2- 3.7 4- 4.2 3.7 3.2 6. 2.