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ln(1+(1/n*sqrt(n)))+1/n

Sum of series ln(1+(1/n*sqrt(n)))+1/n



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The solution

You have entered [src]
  oo                      
____                      
\   `                     
 \    /   /      ___\    \
  \   |   |    \/ n |   1|
  /   |log|1 + -----| + -|
 /    \   \      n  /   n/
/___,                     
n = 1                     
$$\sum_{n=1}^{\infty} \left(\log{\left(\frac{\sqrt{n}}{n} + 1 \right)} + \frac{1}{n}\right)$$
Sum(log(1 + sqrt(n)/n) + 1/n, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\log{\left(\frac{\sqrt{n}}{n} + 1 \right)} + \frac{1}{n}$$
It is a series of species
$$a_{n} \left(c x - x_{0}\right)^{d n}$$
- power series.
The radius of convergence of a power series can be calculated by the formula:
$$R^{d} = \frac{x_{0} + \lim_{n \to \infty} \left|{\frac{a_{n}}{a_{n + 1}}}\right|}{c}$$
In this case
$$a_{n} = \log{\left(1 + \frac{1}{\sqrt{n}} \right)} + \frac{1}{n}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\log{\left(1 + \frac{1}{\sqrt{n}} \right)} + \frac{1}{n}}{\log{\left(1 + \frac{1}{\sqrt{n + 1}} \right)} + \frac{1}{n + 1}}\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
The answer [src]
  oo                      
____                      
\   `                     
 \    /1      /      1  \\
  \   |- + log|1 + -----||
  /   |n      |      ___||
 /    \       \    \/ n //
/___,                     
n = 1                     
$$\sum_{n=1}^{\infty} \left(\log{\left(1 + \frac{1}{\sqrt{n}} \right)} + \frac{1}{n}\right)$$
Sum(1/n + log(1 + 1/sqrt(n)), (n, 1, oo))
Numerical answer
The series diverges
The graph
Sum of series ln(1+(1/n*sqrt(n)))+1/n

    Examples of finding the sum of a series