Problem 5: (a) If f = x y, express f in terms of x, x, y, y', +, . (b) Prove that ( xy) ez=x + (y z). (c) Prove that if x y=z, then x z= y and x y z=0. (d) Prove that x y = x + y if xy = 0. (e) Prove that (a + b) e (a + c) = a'(bec). (f) Prove that x + y=x y xy = x x'y. =