1. Ch 9 Inequalities and Absolute Value
9.1 Sets, Intersection and Unions
Goal(s): 1.) Name sets using set- builder and
roster notation
2.) Find Intersections and Unions of
sets

2. “Set” is a well-defined collection of objects called “members” or “elements”
Wearing sweatshirt
Blue eyes

3. “Roster Notation”
The set of all whole numbers greater than 20 can be written: {21, 22, 23, 24, …}
Use pointed brackets
Three dots, called an ellipsis, indicate that the pattern continues forever, following the pattern set by the first 4 numbers.
List each element

4. Write using “roster notation”
The set of all integers greater than 5 and less than or equal to 10
{6,7,8,9,10}

5. Write using “roster notation”
The set of all prime numbers
less than 12
{2,3,5,7,11}

6. Write using “roster notation”
The set of all positive odd numbers
{1,3,5,7,…}
List the first 4
Then write the ellipsis to show “the pattern continues”

7. Write using “roster notation”
The set of all positive multiples of 3
{3,6,9,12,…}

8. Set-builder Notation Used to describe HOW a set is built, for example
{x|x is a whole number and x > 20}
Description
Means “such that”

9. Write using “set-builder notation”
The set of all integers greater than 7
{x|x is an integer and x > 7}

10. Write using “set-builder notation”
The set of all multiples of 5 that are less than 24
{x|x is a multiple of 5 and x < 24}

11. Use capital letters to name sets
“Z” is used to name the set of all integers
“Q” used for the set of all rational numbers
€means “is an element of”
And € means “is not an element of”

12. Let E be the set of even numbers True or False ? 18 € E

13. Let E be the set of even numbers True or False ? 12 € E

14. Write using “roster notation” and “set builder notation”:
The set G of whole numbers greater than 5
G = {6,7,8,9,…}
G = {x|x is a whole number and x>5}

15. Write using “roster notation” and “set builder notation”:
The set T of multiples of 5 less than 24
T = {20,15,10,5,0,-5,…}
T = {x|x is a multiple of 5 and x < 24

16. Intersection of two sets
Is the set of all members common to both sets.
Written A B (“A intersection B”)
Venn diagram representation: A B

17. A = {1,2,3,4,5,6} B = {-2,-1,0,1,2,3} 1 2 3 A 4 5 6 B -2 -1

18. T = {0,1,6,9} P = {-3,-2,0,1,5} S = {-3,1,6} 1 T 6 9 P -3 -2 5

19. T = {x|x is an even number} P = {y|y is an odd number}

20. Union of two sets A B Is the set of all members either or both sets.
Written AB (“A union B”)
Venn diagram representation: A B

21. Union of two sets A B Is the set of all members either or both sets.
Written AB (“A union B”)
Venn diagram representation: A B

22. A = {1,2,3,4,5,6} B = {-2,-1,0,1,2,3} 1 2 3 A 4 5 6 B -2 -1

26. Assignment: Page 403 (2-42) even