Tuesday, 30 July 2013

algebra precalculus - Prove $left(1+frac1{n}right)^{n}

I am trying to prove the following by mathematical induction:

(1+1n)n<(1+1n+1)n+1


Other proofs without induction are found here: I have to show (1+1n)n is monotonically increasing sequence.
But I am curious whether it can be proved by induction as well.



What I've tried so far:



The original inequality is equivalent to
$$(n+1)^{2n+1}So I have to show:
(n+2)2n+3<(n+1)n+1(n+3)n+2



And,
(n+1)n+1(n+3)n+2=(n+1)nn(1+1n)n(n+3)(n+2)n+1(1+1n+2)n+1
>(n+1)(n+3)(n+1)2n+1(1+1n)n(1+1n+2)n+1
=(n+1)(n+3)(n+2+1n)n(n+1+n+1n+2)n+1

and I am stuck.

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