Question

If $A$ and $B$ are disjoint sets, then $A-B=$ and $B-A=$.

• A. $A$
• B. $B$
• C. $\varphi$
• D. $\left\{0\right\}$

Answer 1

Answer: (A), (B)

The correct options are
A $A$
B $B$

If $A$ and $B$ are disjoint sets, then they have no element in common.
Say, $A=\{1,2,3\}$ and $B=\{4,5,6\}$.
We have $A-B$ to be the set of elements of $A$ which are not in $B$. 1, 2 and 3 are all elements of $A$ which are not in $B$ and thus, $A-B=\{1,2,3\}=A.$
Similarly, $B-A$ is the set of elements of $B$ which are not in $A$. Thus, $B-A=\{4,5,6\}=B.$