# Series error

1. Nov 13, 2008

### lindsaygilber

How many terms of the series do we need to add in order to find the sum to the indicated accuracy?

The alternating series from n=1 to infinity of ((-1)^(n+1))/(n^2)
|error| less than 0.0399

i got it down to 1/n^2 is less than 0.0399 but i can't figure out if n = 5 or n=6... please help:(

Last edited: Nov 13, 2008
2. Nov 13, 2008

### HallsofIvy

If you want 1/n2< 0.0399, then you want 1/0.0399= 25.0626< n2 While it is close hat is NOT true for n= 5.