Sunday, July 29, 2018

The limit $lim_{nto infty}{na^n}=0$

Let $a\in [0,1)$. I want to show that $$\lim_{n\to \infty}{na^n}=0$$



My try : $$na^n={n\over e^{-(\log{a})n}}$$ and the limit is $${+\infty\over +\infty}$$
Hence by l'Hopital's rule we have that
$$\lim_{n\to \infty}{1\over -(\log{a})e^{-(\log{a})n}}={1\over -\infty}=0$$



Is there any other way to compute this limit ? thanks!

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