Webwhompers

The union of two sets A and B is the set consisting of any object that is (1) an element of A, or (2) an element of B, or (3) an element of both A and B. The union of A and B is written as A ∪ B.

Examples:

• {1} ∪ {2,3} = {1,2,3}
• {2} ∪ {2,3} = {2,3}
• { } ∪ {4,6} = {4,6}
• A = {1,2,3,4,5}. B = {3,4,5,6,7,8}.  A ∪ B = {1,2,3,4,5,6,7,8}.

The intersection of A and B is the set of all objects that are elements of both A and B. The intersection of A and B is written as A ∩ B.

Examples:

• {2} ∩ {2,3} = {2}
• {3,2} ∩ {2,3} = {2,3}
• {2,3} ∩ {4,6} = { }
• A = {1,2,3,4,5}. B = {3,4,5,6,7,8}.  A ∩ B = {3,4,5}.

The above examples involving sets A and B can be drawn as the following Venn diagram: