Monday 19 August 2013

sequences and series - Calculate $lim_{nto infty}(n+1)^{frac{1}{sqrt{n}}}$





Calculate the following limit: $$\lim_{n\to \infty}(n+1)^{\frac{1}{\sqrt{n}}}$$




I have tried to use the squeeze theorem and other convergence tests but all failed.



Please, any help?


Answer



Note that




$$1\le(n+1)^{1/\sqrt n}\le(2n)^{1/\sqrt n}=2^{1/\sqrt n}((\sqrt n)^{1/\sqrt n})^2$$



If we take $2^{1/x}$ and $x^{1/x}\to1$ as $x\to\infty$ for granted, then



$$2^{1/\sqrt n}((\sqrt n)^{1/\sqrt n})^2\to1\cdot1^2=1$$



and the Squeeze Theorem does the rest.


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