Let $V =\{a, e, i, o, u\}$ and $B =\{a, i, k, u\} .$ Find $V - B$ and $B - V$
We have, $V - B =\{e, o\},$ since the elements $e, o$ belong to $V$ but not to $B$ and $B - V =\{k\},$ since the element $k$ belongs to $B$ but not to $V$
We note that $V - B \neq B$ - $V$. Using the setbuilder notation, we can rewrite the definition of difference as
$A - B = \{ x:x \in A$ and $x \notin B\} $
The difference of two sets $A$ and $B$ can be represented by Venn diagram as shown in (Fig)
The shaded portion represents the difference of the two sets $A$ and $B$
Using that for any sets $\mathrm{A}$ and $\mathrm{B},$
$A \cup(A \cap B)=A$
If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find
$B \cup C \cup D$
If $X$ and $Y$ are two sets such that $n( X )=17, n( Y )=23$ and $n( X \cup Y )=38$
find $n( X \cap Y )$
If $A=\{3,6,9,12,15,18,21\}, B=\{4,8,12,16,20\},$ $C=\{2,4,6,8,10,12,14,16\}, D=\{5,10,15,20\} ;$ find
$A-B$
If $A = \{ x:x$ is a natural number $\} ,B = \{ x:x$ is an even natural number $\} $ $C = \{ x:x$ is an odd natural number $\} $ and $D = \{ x:x$ is a prime number $\} ,$ find
$C \cap D$