1. Homework Answers 1. {3} 2. {1, 3} 5. {3, 4, 6} 6. {} 10. {2, 3, 4}
11. {1, 3, 4}
14. {5}
16. {3, 4}
22. {}
23. {8}
24. C = {8}
28*. D = {6, 8}
32. B = {2, 4, 8}

2. Lesson 9
Sets and their Union

3. Review on Sets A set is a collection of elements.
A finite set is a set whose number of elements can be counted.
An infinite set is a set whose number of elements CANNOT be counted.
The empty set (or null set) is a set that has NO ELEMENTS { } Or {  }
A subset is a smaller set from a larger set. Symbol for subset is 
The complement of a set is the set of all the elements that belong to a LARGER set but DO NOT belong in a given subset.
The intersection of sets is the set of all the elements that belong to both sets. Symbol for intersection is 

4. Union of Sets
The union of sets is a set that contains all possible elements from both sets without duplicates.
Symbol for union is 
Ex: A  B
Ex: A = {A, B, C, D, E}
B = {A, E, I, O, U}
List the elements of the resulting set
A  B

5. Practice Let A = {1, 2, 3, 4, 5} Let B = {1, 3, 5, 7, 9}
Let C = {2, 4, 6, 8, 10}
Solve the following:
1. A  B 2. A  B 3. B  C 4. C  A
5. C   6. B  C 7. C  C
8. (A  B)  C