Union
Pronunciation: /ˈyun yən/ Explain
 Figure 1: Click on the image to see a representation of C = A ∪ B. 

A union of two or more sets is the set containing
all the members of each of the sets. We say, "Set C
is the union of sets A and B."
We write C = A ∪ B.
Properties of Union of Sets
Property  Math Statement  Description 
Commutative  A ∪ B = B ∪ A  The union of sets is commutative 
Associative  (D ∪ E) ∪ F = D ∪ (E ∪ F)  The union of sets is associative 
Distributive  (D ∩ E) ∪ F = (D ∪ F) ∩ (E ∪ F) (D ∪ E) ∩ F = (D ∩ F) ∪ (E ∩ F)  The intersection and union of sets are distributive 

References
 Goldrei, D.C.. Classic Set Theory: For Guided Independent Study. pg 4. Chapman & Hall Mathematics. July 1, 1996. Last Accessed 1/24/2010. Buy the book
 Gilbert, Jimmie; and Gilbert Linda. Elements of Modern Algebra. 6th edition. pg 5. Thomson, Brooks/Cole. 2005. Buy the book
More Information
 McAdams, David E. Sets. lifeisastoryproblem.com. Life is a Story Problem LLC. 3/12/2009. http://www.lifeisastoryproblem.com/algebra/sets.html.
Cite this article as:
McAdams, David E. Union. 5/5/2011. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/u/union.html.
Image Credits
Revision History
9/15/2008: Expanded 'More Information'. (
McAdams, David E.)
3/28/2008: Added properties of union of sets. (
McAdams, David E.)
8/1/2007: Initial version. (
McAdams, David E.)