Determine whether the ratio test is inconclusive (that is, it fails to give a definite answer), conclusive (convergent), or conclusive (divergent) for each series. (a) ∞ 1 n3 n = 2 inconclusive conclusive (convergent) conclusive (divergent) (b) ∞ n 3n n = 3 inconclusive conclusive (convergent) conclusive (divergent) (c) ∞ (−6)n − 1 n n = 2 inconclusive conclusive (convergent) conclusive (divergent) (d) ∞ 5 n 1 + n2 n = 3 inconclusive conclusive (convergent) conclusive (divergent)