Intersection and union of 2 sets - Set Theory

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Intersection and union of 2 sets

Lessons

Notes:

In this section we will learn about intersection and union of 2 sets.

Let A and B be sets. Then, the definitions for intersection and union is the following:

Intersection: A set of elements where the elements show up both in A and B. We call this intersection A\capB. Sometimes people refer to the symbol \cap as the word "and".

Union: A set of all elements that appears in A, in B, or both in A and B. We call this union A\cupB. Sometimes people refer to the symbol \cup as the word "or".

Here is a definition that may be useful:

A\B: The set of elements that is in A but not in B. In short, it is just A minus B.

The principle of inclusion and exclusion of 2 sets says the following:

n(A\cupB) = n(A) + n(B) - n(A\capB)

  • Intro Lesson
    Introduction to Intersection and Union of 2 Sets
  • 1.
    Finding the Intersection & Union of 2 Sets

    You are given the following Venn diagram:

    Finding the Intersection & Union of 2 Sets

  • 2.
    Consider the following:

    - Universal Set U=U = {1, 2, 3, 4, 5, 6, 7, 8}

    - Set A = {1,2,3,4,5,6}

    - Set B = {2,4,6,8}

  • 3.
    Consider the following:

    - A = {mm=4x,0x3,xIm | m = 4x, 0 \leq x \leq 3, x \in I}

    - B = {nn=2x,0x6,xIn | n = 2x, 0 \leq x \leq 6, x \in I}

  • 5.
    Willy surveyed 30 people at a restaurant to see if they ordered noodles or rice. 10 people ordered both rice and noodles. 5 people only ordered a drink. 3 people ordered only rice.
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Intersection and union of 2 sets

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