Prove the domination laws in Table 1 by showing that
a) A ∪ U = U.
b) A ∩ ∅ = ∅.
Step1:
NOTE: A set A is a subset of a set B , or equivalently B is a superset of A , if A is contained inside B, that is all elements of A are also elements of B. A and B may coincide.That is

UNION: The union of two sets A and B is the set containing all elements that are in A or in B ( possibly both).
Then it is denoted by , we can write if and only if or .
Note :
Example :
A= { a, b} , B = {b ,c} then .
The union of sets A and B is shown by the shaded area in the venn diagram:
Step2:
a)In this problem we need to show that .
Consider , .
By the definition of union (or) .
We know that is a universal set .So , .
Therefore , .
………….(1)
From the definition of the subset and union we get …………(2)
Therefore...