Mister Exam

Other calculators


lnn/n^2

Sum of series lnn/n^2



=

The solution

You have entered [src]
  oo        
____        
\   `       
 \    log(n)
  \   ------
  /      2  
 /      n   
/___,       
n = 1       
$$\sum_{n=1}^{\infty} \frac{\log{\left(n \right)}}{n^{2}}$$
Sum(log(n)/n^2, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{\log{\left(n \right)}}{n^{2}}$$
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
$$a_{n} = \frac{\log{\left(n \right)}}{n^{2}}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left(n + 1\right)^{2} \left|{\log{\left(n \right)}}\right|}{n^{2} \log{\left(n + 1 \right)}}\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
Numerical answer [src]
0.937548254315843753702574094568
0.937548254315843753702574094568
The graph
Sum of series lnn/n^2

    Examples of finding the sum of a series