determine the smallest positive integer N such that the partial sum is within 10^-10 of the series sum.(adsbygoogle = window.adsbygoogle || []).push({});

{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 theres the negative 1/4, how do i get it to be positive? i get the right answer when its positive but im not sure how to do it.

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# Homework Help: Partial Sum with in 10^-10

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