Sets · Second Year
Sets
Second Year · Notation & Venn diagrams · Tap NEXT to begin
Section 1 of 2
Set Notation
The symbols
$\cap$ intersection (in both) $\cup$ union (in either) $A'$ complement (outside) $A\setminus B$ (in $A$, not $B$) $\#A$ how many.
Worked example — intersection and union
$A=\{1,2,3\}$, $B=\{2,3,4\}$. List $A\cap B$ and $A\cup B$.
$A\cap B$ = in both = $\{2,3\}$
$A\cup B$ = in either = $\{1,2,3,4\}$
$A\cap B=\{2,3\}$, $A\cup B=\{1,2,3,4\}$
Section 2 of 2
Venn Diagrams
Two circles inside the universal set $U$. The overlap is the intersection.
Now you try
You try
For the same sets, list $A\setminus B$ (in $A$ but not $B$).
Pen and paper out — try it before you reveal.
$A=\{1,2,3\}$; remove anything also in $B$
$A\setminus B = \{1\}$
$A\setminus B = \{1\}$
That’s Sets.
The notation, listing elements, and reading a two-set Venn diagram.