In the book while doing the ratio test:(adsbygoogle = window.adsbygoogle || []).push({});

as n --> infinity

why do they just have (-1)^(n+1) just disappear in the next step, since it oscillates between -1 and 1, I don't understand how u could just make it disappear in computations. Isn't the limit as n -> infinity , equal to D.N.E.?

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# Ratio test, why does the (-1)^(n+1) disappear?

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