DEFINITIONS
The union of two sets contains all the elements contained in either set (or both sets). The union is notated A ⋃ B.
The intersection of two sets contains only the elements that are in both sets. The intersection is notated A ⋂ B.
Using a Venn Diagram, the union and intersection of two sets can be seen below:
GIVEN
The sets are given to be:
[tex]\begin{gathered} S=\mleft\lbrace1,2,3,\ldots,18,19,20\mright\rbrace \\ A=\mleft\lbrace3,4,8,9,11,13,14,15,20\mright\rbrace \\ B=\mleft\lbrace4,7,13,14,16,18,19\mright\rbrace \end{gathered}[/tex]
QUESTION
1) (A ∪ B): The terms of the two sets contained in either set or the two sets are
[tex](A\cup B)=\mleft\lbrace3,4,7,8,9,11,13,14,15,16,18,19,20\mright\rbrace[/tex]
2) (A ∩ B): The elements that are in both sets are
[tex](A\cap B)=\mleft\lbrace4,13,14\mright\rbrace[/tex]
