Question

For any two sets $A\&B;n(A-B)=$ $\text{and}n(B-A)=$

• A. $n\left(A\right)+n(A\cap B)$
• B. $n\left(A\right)-n(A\cap B)$
• C. $n\left(B\right)-n(A\cap B)$
• D. $n\left(B\right)+n(A\cap B)$

Answer 1

Answer: (B), (C)

$n\left(B\right)-n(A\cap B)$

For any two sets $A\&B$, we know the relation:
$A-B=A-(A\cap B)$
$\Rightarrow n(A-B)=n\left(A\right)-n(A\cap B)$
Similarly, $B-A=B-(A\cap B)$
$\Rightarrow n(B-A)=n\left(B\right)-n(A\cap B)$