# Ratio test, why does the (-1)^(n+1) disappear?

1. Dec 1, 2004

### CinderBlockFist

In the book while doing the ratio test:

as n --> infinity

why do they just have (-1)^(n+1) just disappear in the next step, since it oscillates between -1 and 1, I don't understand how u could just make it disappear in computations. Isn't the limit as n -> infinity , equal to D.N.E.?

2. Dec 1, 2004