umm.which series is that? all i know is that the harmonic series always diverges, GP series always converges, and the p-series always converges for p>1. umm..can u please tell me how to determine which series to compare the un with in limit comparison test?? i can figure it out for certain series, but i never seem to understand what to do with the more complicated ones!!!!..one more question, how do you go about the lagrange thingy???..THANKS IN ADVANCE!!