Center 1 – Union vs



Adv Functions: Union vs. Intersection Name _______________

A set of numbers can be grouped by using _________ as follows:

• {1,2,3,4,5,…} is the infinite set of ____________

• {2, 4, 7, 10} is a ___________ of four numbers. The members, called ________, of this set are the numbers: ____________.

• {5, 9} is a set of_______ elements. The elements are the numbers _______.

• Notice the curly brackets that designate the sets.

|What is the difference between {5, 9} and (5, 9) ? |

| |

|What is a set with no elements in it called? |

There are 2 operations that can be performed on sets: Union, ___, and Intersection, ___.

|UNION |

|The UNION of two sets, written ______, is the set of all elements that belong to either A ___ B. In set-builder notation, this is written: |

| |

|A [pic] B = _______________. |

|INTERSECTION |

|The INTERSECTION of two sets, written _______, is the set of all elements that belong to BOTH A and B. In set-builder notation, this is written: |

| |

|A [pic] B = _____________ |

Example

Given Set A = {2, 3, 5, 6} and Set B = {2, 4, 6, 8}

1. Find A [pic] B 2. Find A [pic] B

Think union = marriage. Marry the 2 Think: a car intersection is where 2 roads

sets together into one family. overlap. Think where are the 2 sets the same?

A [pic] B = A [pic] B =

To visualize the two set operations, Venn Diagrams can be used. The previous example would look like this:

Set A = {2, 3, 5, 6} Set B = {2, 4, 6, 8}

Given the Venn Diagram, determine what is in Set C and Set D.

Set C = ______________________ Set D = _________________________

C [pic] D = _____________________ C [pic] D = _______________________

Example 3. A school offers three activities, basketball (B), choir (C) and drama (D). Every student must participate in at least one activity.

16 students play basketball only.

18 students play basketball and sing in the choir but do not do drama

34 students play basketball and do drama but do not sing in the choir.

27 students are in choir and do drama but do not play basketball.

(a) Working with a partner, create a Venn diagram, and enter the above information.

-----------------------

Set A

Set B

Set D

Set C

snakes

dogs

hamsters

cats

birds

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