A= {1, 3, 5, 7, 9} b = {2, 4, 6, 8, 10} c = {1, 5, 6, 7, 9} a ∪ b =

If A = {1,3,5,7,9}, B = {1,5,6,7} and C = {1,2,4,6,8,9} find: i) A U B That mean to list all numbers that are either in A, in B, or in both. So A U B = {1,3,5,6,7,9}, for they are in A, B or both. ii) the complement of (A U B) That means to list all the numbers that are listed in one of the sets above but which are NOT in A U B, which we just found in i): Complement of A U B is {2,4,8}, for these are the ones not in A U B iii) the intersection of B and C This means to list ONLY the ones that are in BOTH B and C Intersection of B and C = {1,6} iv) find n(A U B) That means to count the elements in A U B. There are 6. v) list all the subsets of B B = {1,5,6,7} There is just one subset with no members, the empty set, or There are four subsets with just one member: {1}, {5}, {6}, {7} There are six subsets with two members: {1,5), (1,6), (1,7}, {5,6}, {5,7}, {6,7} There are four subsets with three members: (1,5,6), (1,5,7}, {1,6,7}, {5,6,7} There is just one subset with four members, namely the whole set A: {1,5,6,7} So altogether there are 1+4+6+4+1 or 16 subsets of {1,5,6,7}.

The U sign basically means those 2 specific sets numbers put together into a set. So A's set and B's set put together would be {1,2,3,4,5,6,7,8,9,10}