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

(N/A) Let $U = \mathbb{N}$ be the set of natural numbers.
The complement of a set $A$,denoted by $A^\prime$,is defined as $A^\prime = U - A$.
Given $A = \{ x : x \text{ is an odd natural number} \}$.
Therefore,$A^\prime = \{ x : x \in \mathbb{N} \text{ and } x \text{ is not an odd natural number} \}$.
Since a natural number is either odd or even,the complement of the set of odd natural numbers is the set of even natural numbers.
Thus,$A^\prime = \{ x : x \text{ is an even natural number} \}$.