# Homework Help: Limit problem

1. Nov 11, 2012

### Bipolarity

1. The problem statement, all variables and given/known data

Evaluate $$lim_{n→∞} \frac{ (n+1)^{\frac{1}{n+1}} }{n^{\frac{1}{n}}}$$

2. Relevant equations

3. The attempt at a solution
This is actually a part of a series problem I am trying to solve using the ratio test.I can't seem to figure out this limit and L'Hopital's doesn't work. Any hints?

BiP

2. Nov 11, 2012

### jbunniii

Note that if $\lim_{n \rightarrow \infty} n^{1/n}$ exists, let's call it $L$, then both the numerator and denominator converge to $L$, so the limit of the fraction is 1.

Indeed, $\lim_{n \rightarrow \infty} n^{1/n}$ does exist, so focus on proving that fact.

3. Nov 11, 2012

### Helpeme

hey i think the limit is 1

1/(n+1) → 0
and
1/n → 0

if both powers will go → 0 then everything0 = 1

then you get 1/1 = 1

4. Nov 11, 2012

### jbunniii

The answer is right, but the argument is invalid. It's true that $x^{1/n} \rightarrow 1$ if $x$ is a fixed positive number, but here we have $x$ growing to infinity while the exponent shrinks to zero. It is not automatically true that the limit will be 1.

Consider for example
$$\lim_{n \rightarrow \infty} (n^n)^{1/n}$$
Surely this does not converge to 1, since $(n^n)^{1/n} = n$.