Question

a intersection(a union b)=a

Answer 1

U can easily visualize it by venn diagram.....

Answer 2

a intersection(a union b)
=(a inter a )union (a inter b)
=a union (a inter b) [as a inter b is always subset of a as well it can be said that a inter b is a subset of b]
=a union(subset of a )
= a

Answer 3

ny ways what nitz pointed is correct its easy to visualize through Venn Diagram..