factorial vs powers

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Masum
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factorial vs powers

Unread post by Masum » Mon Feb 09, 2015 6:02 am

Prove that, for all real number $r$, there is a constant $n(r)$ so that
\[n!>r^n\]
for all $n\geq r(n)$.
One one thing is neutral in the universe, that is $0$.

Nirjhor
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Re: factorial vs powers

Unread post by Nirjhor » Mon Feb 09, 2015 1:08 pm

If $n,n(r)\in\mathbb N$, I think it suffices to show that $\sqrt[n]{n!}$ is increasing, so eventually it will get past any constant $r$. Indeed we have $\sqrt[n]{n!}<\sqrt[n+1]{(n+1)!}\Leftrightarrow n!^{n+1}<(n+1)!^n\Leftrightarrow n!<(n+1)^n$ which is obviously true for all $n$.
- What is the value of the contour integral around Western Europe?

- Zero.

- Why?

- Because all the poles are in Eastern Europe.


Revive the IMO marathon.

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