How do you use the direct Comparison test on the infinite series sum_(n=2)^oon^3/(n^4-1)n=2n3n41 ?

1 Answer
Sep 8, 2014

Since n^3/{n^4-1} geq n^3/n^4=1/nn3n41n3n4=1n for all n geq2n2 and sum_{n=2}^infty1/nn=21n is a harmonic series, which is known to be divergent, we may conclude that sum_{n=2}^inftyn^3/{n^4-1}n=2n3n41 also diverges by Direct Comparison Test.