Question

If A and B are two sets such that $A\subset B$, then write B' - A' in terms of A and B.

Answer 1

Let $xϵB^{\prime }-A^{\prime }$

$\Rightarrow xϵB^{\prime }andx\text{/}ϵA^{\prime }$

$\Rightarrow x\text{/}ϵBandxϵA$

$\Rightarrow x\text{/}ϵBandxϵB$ ($\because A\subset B)$

So B' - A' is an empty set.