Suppose that an≠0, for every n and that L=lim|an+1an| exists. Show that if L < 1, then liman=0.
What I did so far:
If L < 1 and L=lim|an+1an|, there exists n0 such that for n≥n0, 0<|an+1|<|an|. That means that the sequence (|an|)n≥n0 is decreasing.
Consider the set S={|a0|,...,|an0}. S is finite. Let β=max0≤i≤n0|ai|. Thus, (|an|) is limited (because, for every n, 0≤|an|≤β).
Now I have that (|an|) is limited and, throwing away a finite number of terms (the n0 firsts) I can assume that it is decreasing. So I know that $(|a_n|) converges.
How can I prove that it converges to 0?
I also know that if I prove that lim|an|=0, then I have that liman=0.
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