f (x, y) = 4x3 + 9xy + 4y' Local maxima are Local minima are Saddle points are f(x, y) = x3 + 93 + 3x2 -5y -1 Local maxima are Local minima are Saddle points are f(x, y) = x3 + 63 - 3x2 -181 -432y Local maxima are Local minima are Saddle points are