Question

Let $A\subset B$ then $A^{\prime }\cap B^{\prime }=$

• A. $A^{\prime }$
• B. $B^{\prime }$
• C. $B$
• D. none of these

Answer 1

The correct option is B $B^{\prime }$

Now, given $A\subset B$.

This gives $A\cup B=B$......(1).

Now,

$A^{\prime }\cap B^{\prime }$

$=(A\cup B{)}^{\prime }$ [ Using De Morgan's law]

$=B^{\prime }$. [ Using (1)]