How do we find out if they are negative, positive, or zero?

7. Consider level curves for the function z = f(x, y) . Use the contour plot to answer each question below. (20) y -1 f =0 3f= f =2 f =3 -16- A) fx(-1, -5) is positive, negative, or zero) B) fy(-1, -5) is (positive, negative, or zero) C) fxx (-1, -5) is (positive, negative, or zero) D) fyy (-1, -5) is positive, negative, or zero) E) fry (-1, -5) is (positive, negative, or zero)