Basic Set Notation

Problem 1: Mrs. Glosser asked Kyesha, Angie and Eduardo to join the new math club. After school they signed up and became members. They wrote about it on the chalkboard using set notation:

P = {Kyesha, Angie and Eduardo}

When Angie’s mother came to pick her up, she looked at the chalkboard and asked: What does that mean?

Solution: Let P be the set of all members in the math club.

An object that belongs to a set is called an element (or a member) of that set. We use special notation to indicate whether or not an element belongs to a set, as shown below.

Symbol	Meaning
	is an element of
	is not an element of

For example, given the set A = {1, 2, 3, 4, 5}, we can write 1  A, which stands for 1 is an element of set A. We can also write 7  A, which stands for 7 is not an element of set A. Let’s look at some more examples of this.

Set	Notation	Meaning
A = {2, 4, 6, 8}	2  A	2 is an element of A
	5  A	5 is not an element of A
B = {a, e, i, o, u}	e  B	e is an element of B
	w  B	w is not an element of B
C = {1, 3, 5, 7, 9}	7  C	7 is an element of C
	2  C	2 is not an element of C
D = {-3, -2, -1, 0, 1, 2, 3}		-2 is an element of D
		One-half is not an element of D

Determine if the given item is an element of the set.
Set	Item	Is an element?
R = {2, 4, 6, 8}	10
S = {2, 4, 6, 8, 10}	10
D = {English alphabet}	m
D = {English alphabet}
X = {prime numbers less than 10}	9
A = {even numbers}	8

Summary: An object that belongs to a set is called an element (or a member) of that set. We use special notation to indicate whether or not an element belongs to a set: (),

Exercises

Directions: Read each question below. Select your answer by clicking on its button. Feedback to your answer is provided in the RESULTS BOX. If you make a mistake, rethink your answer, then choose a different button.

1.	Which of the following is a true statement for set R? R = {liquid, gas, solid, plasma}
	gas  R  solid  R  liquid  R  None of the above.RESULTS BOX:

2.	Which of the following is true for set G?G = {1, 3, 5, 7, 9}
	5   G  7  G  3  G  All of the above.RESULTS BOX:

3.	Which of the following statements is true about set B?B = {US flag colors}
	red  B  blue  B  white  B  All of the above.RESULTS BOX: