Question

Show that if a is the subset of b then a union b=b

Answer 1

Taking A = { 1 , 2 }

B = { 1 ,2 ,3 } and A ⊂ B .

Now A ∪ B = { 1 ,2 } ∪ { 1 , 2 , 3 }

= { 1 , 2 , 3 }

= B .

Hence for every A ⊂ B , A ∪ B = B .

Hope helped !