Mister Exam

Other calculators


(3-sin*n)/n-lnn

Sum of series (3-sin*n)/n-lnn



=

The solution

You have entered [src]
  oo                       
 ___                       
 \  `                      
  \   /3 - sin(n)         \
   )  |---------- - log(n)|
  /   \    n              /
 /__,                      
n = 1                      
$$\sum_{n=1}^{\infty} \left(- \log{\left(n \right)} + \frac{3 - \sin{\left(n \right)}}{n}\right)$$
Sum((3 - sin(n))/n - log(n), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$- \log{\left(n \right)} + \frac{3 - \sin{\left(n \right)}}{n}$$
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
$$a_{n} = - \log{\left(n \right)} + \frac{3 - \sin{\left(n \right)}}{n}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty} \left|{\frac{\log{\left(n \right)} + \frac{\sin{\left(n \right)} - 3}{n}}{\log{\left(n + 1 \right)} + \frac{\sin{\left(n + 1 \right)} - 3}{n + 1}}}\right|$$
Let's take the limit
we find
$$1 = \lim_{n \to \infty} \left|{\frac{\log{\left(n \right)} + \frac{\sin{\left(n \right)} - 3}{n}}{\log{\left(n + 1 \right)} + \frac{\sin{\left(n + 1 \right)} - 3}{n + 1}}}\right|$$
False
The rate of convergence of the power series
The graph
Sum of series (3-sin*n)/n-lnn

    Examples of finding the sum of a series