A Union B Formula
The union of two sets A and B is a set that contains all the elements of A and B and is denoted by A U B (which can be read as "A or B" (or) "A union B"). A union B formula is used to find the union of two sets A and B. The union can be found by just putting all the elements of A and B in one set and removing duplicates. i.e., A U B can be found without using the A union B formula also. Let us learn about the A union B formula with a few examples in the end.
What Is the A Union B formula?
The union of two sets is represented by writing the symbol "U" in between the two sets. By using the above definition, the A union B formula is,
A U B = {x : x ∈ A (or) x ∈ B}
This formula means that any element that is present either in A or in B is present in A U B. Let us see the applications of A union B formula in the following section.

Example 1: If A = {1, 2, 3, 4} and B = {2, 3, 6, 7} then find A U B.
Solution:
To find: A U B.
Given that:
A = {1, 2, 3, 4}
B = {2, 3, 6, 7}
By using the A union B formula, we find A U B just by writing all the elements of A and B in one set by avoiding the duplicates.
So, A U B = {1, 2, 3, 4} U {2, 3, 6, 7} = {1, 2, 3, 4, 6, 7}
Note: The elements in the answer set do not need to be in order.
Answer: A U B = {1, 2, 3, 4, 6, 7}.

Example 2: Find A U B using the following figure.
Solution:
To find: A U B.
By using the A union B formula, we find A U B just by writing all the elements of A and B in one set by avoiding the duplicates.
Thus, by the given Venn Diagram, A U B = {11, 20, 14, 2, 10, 15, 30}.
Note: 14, 16, 3, and 18 are neither the elements of A nor the elements of B and hence they are not present in A U B.
Answer: A U B = {11, 20, 14, 2, 10, 15, 30}.