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) [infinity] 4 n3 n = 3 inconclusive conclusive (convergent) conclusive (divergent) (b) [infinity] n 2n n = 2 inconclusive conclusive (convergent) conclusive (divergent) (c) [infinity] (−6)n − 1 n n = 1 inconclusive conclusive (convergent) conclusive (divergent) (d) [infinity] 4 n 1 + n2 n = 3 inconclusive conclusive (convergent) conclusive (divergent)