Question

Find the radius of convergence, R, of the series.

Answer 1

\[\sum_{n=1}^{\infty}\frac{ (5x-4)^n }{ n5^n }\]

Answer 2

Anyone want to tell me what I exactly have to do here? :/ . I know what the radius of convergence means.

Answer 3

I'd give the ratio test a go. It converges when L<1 but this time L will be dependent on x so your condition on the convergence based on x will give you the interval within which it converges

Answer 4

I tried that but it didn't work...