Question

If A = {x : x is a multiple of 3} and , B = {x :x is a multiple of 5}, then A - B is

• A. $A\cap B$
• B. $A\cap \overline{B}$
• C. $\overline{A}\cap \overline{B}$
• D. $\overline{A\cap B}$

Answer 1

The correct option is B

$A\cap \overline{B}$

A = {x : x is a multiple of 3}

A = {3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,...}

B = {x : x is a multiple of 5}

B = {5,10,15,20,25,30,35,40,45,50,...}

Now, we have :

A - B = {3,6,9,12,18,21,24,27,33,36,39,42,48,...} = $A\cap \overline{B}$