Question 2. Consider the logical equivalence: p (4r) = (p^9) r Hint: If statement forms P and Q are logically equivalent, then P +Q is a tautology. Conversely, if P + Q is a tautology, then P and Q are logically equivalent. (a) Without using a truth table, verify that statement forms p (r) and (pAq)r are logically equivalent. (b) Is p (q r) (p^q)r a tautology? Explain without using a truthtable. (c) Then, use a truth table to verify that p- (qr) (pAq)r is a tautology