5. (2.4 Sequences and Summations) Find a solution to the recurrence relation an = 2n-1 +n given the initial condition that a, = 1. a. an = 1 + n(n+1) b. Q = 1+na+n C. an = 1+ n(n+1)/2 d. An = 1+n! 6. (1.3 Propositional Equivalences) Determine if the following is a contingency, contradiction, tautology, or implication. (pv)^(-p Vr) - (p Vr) a. contingency b. tautology C. contradiction d. implication