Question 7 (12 marks) Consider the function f (x, y) = vy-x - a. State the domain of f (x, y ) in set notation dom (f ) = {(x, y) = R2 :...} and sketch it in the x - y plane. (2 marks) b. State the range of f (x, y) in set notation R(f)= ZER:...) and sketch it on the real line. (2 marks) c. Sketch the level curves of = = f (x, y ) for = =0, z =1 and z =2. (3 marks) d. Find f, and fy (2 marks) e. Find the gradient vector Vf at the point (0,1) and include it in your sketch in part c