Let $A = \{1, 2, 3, 4, 5, 6\}$. Insert the appropriate symbol $\in$ or $\notin$ in the blank space:
$0 \dots A$

Let $A$ and $B$ be sets. If $A \cap X = B \cap X = \phi$ and $A \cup X = B \cup X$ for some set $X$,show that $A = B$. (Hint: Use $A = A \cap (A \cup X)$,$B = B \cap (B \cup X)$ and the Distributive law.)

The set $A = \{ x : x \ne x \}$ represents:

If ${N_a} = \{an : n \in N\}$,then ${N_3} \cap {N_4} = $

Let $A = \{1, 2, 3, 4, 5, 6\}$. Insert the appropriate symbol $\in$ or $\notin$ in the blank space:
$8 \dots A$

Examine whether the following statement is true or false:
$\{a\} \in \{a, b, c\}$