MHB Why Is the Limit of This $\ln$ Sequence Incorrect?

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The sequence in question is defined as \( a_n = \ln\left({\frac{n}{n^2 + 1}}\right) \). The limit being evaluated is \( \lim_{{n}\to{\infty}} \ln\left({\frac{n}{n^2 + 1}}\right) \), which involves first finding the limit of \( \frac{n}{n^2 + 1} \) as \( n \) approaches infinity. While this limit approaches 0, substituting this directly into the logarithm leads to \( \ln(0) \), which is undefined and results in negative infinity. The error lies in the incorrect assumption that the limit of the logarithm can be determined simply by evaluating the limit of its argument without considering the behavior of the logarithm near 0. Therefore, a more careful analysis of the logarithmic function's limit is required.
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If I have this sequence

$$a_n = \ln\left({\frac{n}{n^2 + 1}}\right)$$

I need to find:

$$ \lim_{{n}\to{\infty}} \ln\left({\frac{n}{n^2 + 1}}\right)$$

Shouldn't I be able to find the limit of$$ \lim_{{n}\to{\infty}} \frac{n}{n^2 + 1}$$ (which is $0$) and then substitute the result of that into the original limit and get the answer there?

So if I substitute in 0 I would get

$$ \lim_{{n}\to{\infty}} \ln\left({0}\right)$$

which would be negative $\infty$. However this is the incorrect answer.
 
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Why do you think that the result is incorrect?
 
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