Question

If A = {4, 5, 6}; B = {7, 8}, then show that A ∪ B = B ∪ A.

Answer 1

Given sets are 

A = {4, 5, 6} and B = {7, 8} 

A ∪ B = {4, 5, 6} ∪ {7, 8} 

= {4, 5, 6, 7, 8}. 

B ∪ A = {7, 8} ∪ {4, 5, 6} 

= {4, 5, 6, 7, 8} 

∴ A ∪ B = B ∪ A.