Good evening, I'm an electrical engineering student questioning my answer to this series Region of Convergence problem.(adsbygoogle = window.adsbygoogle || []).push({});

Ʃ(0,inf) (n(n-1)(z+5i)^n)/n

Using the ratio test lim n-> |an+1/an|

I was able to get it down to lim n->|n(z+5i)/(n-1)| which gave |inf/inf| = 1, which means the test fails. What do I do to properly solve this? :(

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# Complex Series, Region of Convergence

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