A difficult Series problem!

gavin25

1. The problem statement, all variables and given/known data
Show that the series Ʃ 1 to ∞ ((-1)^n)*(n+1)/5^n converges using the alternating series test.


2. Relevant equations



3. The attempt at a solution
I don't know how to show the series is decreasing. I took the derivative of the function, but it got messy and I don't feel that was the correct way to go. Any help appreciated, thanks.
1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution

LCKurtz

Have you played with the inequality you get when you write ##a_{n+1}\le a_n##? Show us what you get...