1. For the set X = {a, b, c, d, e}, list all of the subsets having exactly two elements. How many are there? Question 2. Let U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}, and define A = {3, 6, 9, 12}, B = {4, 8, 12}, C = {6, 12}. Determine each of the following. (i) A B (ii) A C 0 (iii) (A C) B (iv) ((A B) C) 0 Question 3. Define the sets A = {x : x = 2k for some positive integer k}, B = {x : x = 3k for some positive integer k}. Describe the sets AB and AB using set-builder notation, and also explicitly list the first eight elements for each of the sets A B and A B