If the sets $A$ and $B$ are defined as $A = \{ (x,\,y):y = {1 \over x},\,0 \ne x \in R\} $ $B = \{ (x,y):y = - x,x \in R\} $, then
$A \cap B = A$
$A \cap B = B$
$A \cap B = \phi $
None of these
If $A$ and $B$ are any two sets, then $A \cup (A \cap B) $ is equal to
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\} $
Let $A=\{1,2,3,4,5,6\}, B=\{2,4,6,8\} .$ Find $A-B$ and $B-A$
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
$A-C$
If $A = \{x : x$ is a multiple of $4\}$ and $B = \{x : x$ is a multiple of $6\}$ then $A \cap B$ consists of all multiples of