The Union of two sets is the set of elements which are in either set.
Example: A = {1,2,3}, B = {3,4,5}. The UNION of A and B, written AU B = {1, 2, 3, 4, 5}. Notice how none of the numbers are repeated in the final set. Though there is a 3 in set A and a 3 in set B, there is only one 3 in set A U B.The Intersection of two sets is the set of elements which are in all of the selected sets.
Example: A = {3,5,9}, B = {5, 9, 11}. The INTERSECTION of A and B, written A ∩ B = {5, 9}. Again, multiple numbers are not repeated.
