please answer number 2 with a truth table. skip 3. answer 4 eithout truth table

(2) (5 pts) Is (p +9) r the negation of (7V9)^7 ? Justify your answer. (3) (5 pts) Fill the blank in the following with either q or 7 so that the resulting wff is a tautology: (p q) v (p...). Justify your answer. (4) (15 pts) Consider the following arguments. If an argument is valid, then present a proof sequence; otherwise, prove that the argument is invalid. You are forbidden to use truth tables to justify your answers (but, you may use them otherwise). (4a) ((p r) (7 + r)) ((PV) -r) (4b) ((q + r) ^ (p (q V r>>> -> Pr) (4c) ( (q^r)) ^ ( F) A (s D))