Question

Let $A,B$ are complementary subsets of $U$. Then

• A. $A\cup B=\varphi$
• B. $A-B=\varphi$
• C. $A-B=B$
• D. $A\cup B=U$

Answer 1

The correct option is D $A\cup B=U$

Given $A,B$ are complementary subsets of $U$.

Solving this sum by taking an example:

Let U={1,2,3,4,5,6}

Let Set A = {1,3,6} then Set B = {2,4,5}

As Sets A & B are complementary.

Therefore by defintion,

$A\cup B=U$.