Question

For any set $A,$ if $U$ is the universal set, then $A^{\prime }=$

• A. $\{x:x\notin A\mathrm{and}x\in U\}$
• B. $\{x:x\in A\}$
• C. $\{x:x\in U\}$

Answer 1

The correct option is A $\{x:x\notin A\mathrm{and}x\in U\}$

For the set $A$, it's complement is defined by $A^{\prime }=U-A.$
$\Rightarrow A^{\prime }=\{x:x\notin A\text{and}x\in U\}$