Show that $A \cup B=A \cap B$ implies $A=B$.
Let $a \in A.$ Then $a \in A \cup$ $B$. Since $A \cup B=A \cap B, a \in A \cap B$.
So $a \in B$
Therefore, $A \subset$ $B.$ Similarly, if $b \in B$, then $b \in A \cup$ $B.$
Since $A \cup B=A \cap B, b \in A \cap B .$ So, $b \in A .$
Therefore, $B \subset A .$ Thus, $A=B$
If $A=\{3,5,7,9,11\}, B=\{7,9,11,13\}, C=\{11,13,15\}$ and $D=\{15,17\} ;$ find
$\left( {A \cap B} \right) \cap \left( {B \cup C} \right)$
$A-(A-B)$ is
Given the sets $A = \{ 1,\,2,\,3\} ,\,B = \{ 3,4\} , C = \{4, 5, 6\}$, then $A \cup (B \cap C)$ is
Find the union of each of the following pairs of sets :
$A = \{ x:x$ is a natural number and $1\, < \,x\, \le \,6\} $
$B = \{ x:x$ is a natural number and $6\, < \,x\, < \,10\} $
If $A=\{x \in R:|x|<2\}$ and $B=\{x \in R:|x-2| \geq 3\}$ then