Mathematics
Presenter Name : Mr. Pramote Phothisai
Topic : Sets
Subtopic : Union of sets
Objective
1. Explain meaning of the Union of sets.
2. Find the Union of two sets.
elements denoted diagram
covers
Union both represents
region
same
Interesting Words
Phrases referring to what we will talk about
The union of two sets
Is the set of all elements
The same elements of sets
The Venn diagram
That belongs to
Given the set
What is the elements of set A?
A = {2, 5, 8, 9, 11}
and B = {3, 5, 7, 8, 10}
Elements of set A are
What is the elements of set B?
Elements of set B are
2,
5,
8,
9,
11
3,
5,
7,
8,
10
Set A
What are the same elements of sets A and B?
= {2, 5, 8, 9, 11}
and B = {3, 5, 7, 8, 10}
The same elements of sets A and B are
5,
8
The union of two sets, A and B, denoted by
Union of sets
is the set of all elements
A Bthat belongs to A or B or both.
Example 1
(a) Find A B
Let A = {1, 3, 4, 9, 11}and B = {9, 11, 13}
Solution
(b) n(A B) =
(a) A B = {1,
3,
4,
9,
11,
13}
6
(b) Find n(A B)
Example 2
(a) Find P Q
Let P = {1, 3, 6, 8}
and Q = {2, 4, 6, 8, 10}
Solution (b) n(P Q) =
(a) P Q = {1, 2, 3, 4, 6, 8,
10}
7
(b) Find n(P Q)
The colored region in the Venn diagram belowrepresents A B. It covers both the regions representing A and B.
A B = {x : x A or x B}
Try It !
(a) Find M N
Let M = {a, b, d, e} and N = {d, e, k}
? ? ?
(b) Find n(M N)
Let M = {a, b, d, e} and N = {d, e, k}
Solution M N =
n(M N) =
{a, b, d, e, k}
5
OK. That’s it for today.
See you next time.
Thank you for your attention