Let $U=\{1, 2, 3, 4, 5, 6, 7, 8, 9\}$,$A=\{1, 2, 3, 4\}$,$B=\{2, 4, 6, 8\}$,and $C=\{3, 4, 5, 6\}$. Find $(A \cup B)'$.

If $A$ and $B$ are two sets,then $(A \cap B)'$ is equal to

For each positive real number $\lambda$,let $A_\lambda$ be the set of all natural numbers $n$ such that $|\sin(\sqrt{n+1}) - \sin(\sqrt{n})| < \lambda$. Let $A_\lambda^c$ be the complement of $A_\lambda$ in the set of all natural numbers. Then,

If $U = \{a, b, c, d, e, f, g, h\}$,find the complement of the set $C = \{a, c, e, g\}$.

Taking the set of natural numbers as the universal set,write down the complement of the following set:
$A = \{ x : x \text{ is an odd natural number} \}$

If $U = \{a, b, c, d, e, f, g, h\}$,find the complement of the set $A = \{a, b, c\}$.