Chapter 1 supplemental exercises 35 1.69. let a {1, 2, 3) and b = (2, 3, 4). determine the following (a) (a x b)n (b x a) (b) (an b) x (bna) x 1.70. let r= {(1, 1), (2, 1), (3, 2), (3, 3), (4, 2), (4, 3)} be a collection of ordered pairs. find subsets a, b, c, d of the set (1, 2, 3, 4) such that r = ((a x b)u (c x d)) - (d x d). 1.71. for i= 1, 2, 3, let a; = (i, i + 1]. determine u(a x ad 1.72. for a = {1, 2} and b = {3, 4), it follows that p = {a, b} is a partition of the set s = {1,2,3,4). describe a partition of s x s in terms of cartesian products of the sets a and b.