- #1
mattmannmf
- 172
- 0
determine the smallest positive integer N such that the partial sum is within 10^-10 of the series sum.
{Sigma} 2(-1/4)^(n-1) < 10^-10
ok divide the 2 out
(-1/4)^(n-1) < 5^-10
I know i have to take the natural log like so:
(n-1) ln|-1/4| < nl|5^-10|
But there's the negative 1/4, how do i get it to be positive? i get the right answer when its positive but I am not sure how to do it.
{Sigma} 2(-1/4)^(n-1) < 10^-10
ok divide the 2 out
(-1/4)^(n-1) < 5^-10
I know i have to take the natural log like so:
(n-1) ln|-1/4| < nl|5^-10|
But there's the negative 1/4, how do i get it to be positive? i get the right answer when its positive but I am not sure how to do it.