Question

Let A = {3,6,12,15,18,21},

B= {4,8,12,16,20},

C = {2,4,6,8,10,12,14,16} and

D = {5,10,15,20}. Find :

(i) A - B (ii) A - C

(iii) A - D (iv) B - A

(v) C - A (vi) D - A

(vii) B - C (viii) B - D

Answer 1

We have

A = {3,6,12,15,18,21}

B= {4,8,12,16,20}

C= {2,4,6,8,10,12,14,16}

D= {5,10,15,20}

If A and B are two sets, then the set A - B is defined as

A - B = {$xϵA:x\text{/}ϵB$}.

(i) A - B = {$xϵA:x\text{/}ϵB$ } = {3,6,15,18,21}

(ii) A - C = {$xϵA:x\text{/}ϵC$} = {3,15,18,21}

(iii) A - D = {$xϵA:x\text{/}ϵD$} = {3,6,12,18,21}

(iv) B - A = {$xϵB:x\text{/}ϵA$ }

= {4,8,16,20}

(v) C - A {$xϵC:x\text{/}ϵA$} = {2,4,8,10,14,16}

(vi) D - A = {$xϵD:x\text{/}ϵA$ } = {5, 10, 20}

(vii) B - C = {$xϵB:x\text{/}ϵC$ } = {20}

(viii) B - D = {$xϵB:x\text{/}ϵD$ } = {4,8,12,16}