If $X = \{ {4^n} - 3n - 1:n \in N\} $ and $Y = \{ 9(n - 1):n \in N\} ,$ then $X \cup Y$ = . . . . .
The shaded region in the given figure is
If $A, B$ and $C$ are non-empty sets, then $(A -B) \cup (B -A)$ equals
If $A$ and $B$ are two sets such that $A \subset B$, then what is $A \cup B ?$
If $A$ and $B$ are not disjoint sets, then $n(A \cup B)$ is equal to