Question

for all sets A and B, A U (B-A) = A U B. Prove

Answer 1

We can rewrite this as
AU(B\A)
Let us take A={1,2,3} B={3,4,5}
= {1,2,3}U{4,5}
AU(B\A)={1,2,3,4,5}——1
Where as AUB={1,2,3,4,5}——2
From one and two we can pt AU(B\A)=AUB