Mister Exam

Other calculators


1/7+1/27+1/(2n-1)*(2n+5)

Sum of series 1/7+1/27+1/(2n-1)*(2n+5)



=

The solution

You have entered [src]
  oo                        
 ___                        
 \  `                       
  \   /             2*n + 5\
   )  |1/7 + 1/27 + -------|
  /   \             2*n - 1/
 /__,                       
n = 1                       
$$\sum_{n=1}^{\infty} \left(\left(\frac{1}{27} + \frac{1}{7}\right) + \frac{2 n + 5}{2 n - 1}\right)$$
Sum(1/7 + 1/27 + (2*n + 5)/(2*n - 1), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\left(\frac{1}{27} + \frac{1}{7}\right) + \frac{2 n + 5}{2 n - 1}$$
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
$$a_{n} = \frac{34}{189} + \frac{2 n + 5}{2 n - 1}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left|{\frac{34}{189} + \frac{2 n + 5}{2 n - 1}}\right|}{\frac{34}{189} + \frac{2 n + 7}{2 n + 1}}\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
The answer [src]
oo
$$\infty$$
oo
Numerical answer
The series diverges
The graph
Sum of series 1/7+1/27+1/(2n-1)*(2n+5)

    Examples of finding the sum of a series