Let P(x, y) be a propositional function. Show that is a tautology.

Solution :Step 1: In this problem we need to prove that the propositional functions x and are tautology . Step 2: definition :-Tautology : if two propositions have same truth then this is called tautology .Example : let P(x) and Q(x) are two propositions.Where P(x) = “0 is the natural number “ and Q(x) = “ 4 is prime number “Clearly P(x) and Q(x) both are false statement, so this is called tautology .