Question

If A = {3, 6, 9, 12, 15, 18,21}, B = {4, 8, 12, 16, 20}; then check whether A ∪ B = B ∪ A and A – B = B – A

Answer 1

A ∪ B = {3,6,9,12,15,18,21}∪

{4,8,12,16,20} 

= {3,4,6,8,9,12,15,16,18,20,21} 

B ∪ A = {4,8,12,16,20} ∪ 

{3,6,9,12,15,18,21} 

= {3,4,6,8,9,12,15,16,18,20,21} 

A ∪ B = B ∪ A 

A – B = {3,6,9,12,15,18,21} – {4,8,12,16,20} 

= {3,6,9,15,18,21} 

B – A= {4,8,12,16,20} – {3,6,9,12,15,18,21} 

= {4,8,16,20} 

A – B ≠ B – A