In this section we will see solved problems of unit 7 lesson 1 .

Example 1:

Example 2:

Solution:

It can be rewritten as

therefore its valid

Example 3:

Solution:

It can be rewritten as

Since its tautology  its valid

Example 4:

Solution:

It can be rewritten as

Since its tautology therefore its valid

Example 5:

Solution:

Since its not tautology therefore invalid

Example 7:

Solution:

Example 8:

Solution: