Mister Exam
Other calculators
- Taylor Series Step by Step
- Fourier series step by step
- Differential equations Step by Step
- Product of series
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How to use it?
- Sum of series:
-
1/(3n+2)(3n+1)
-
sin(1/n^2)
-
factorial(n)/(n^3+n^2+4)
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1/n/(n-1)/n!
-
Identical expressions
- one /n/(n- one)/n!
- 1 divide by n divide by (n minus 1) divide by n!
- one divide by n divide by (n minus one) divide by n!
- 1/n/n-1/n!
- 1 divide by n divide by (n-1) divide by n!
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Similar expressions
- 1/n/(n+1)/n!
Sum of series 1/n/(n-1)/n!
The solution
You have entered
[src]
oo ____ \ ` \ / 1 \ \ |---------| ) \n*(n - 1)/ / ----------- / n! /___, n = 1
$$\sum_{n=1}^{\infty} \frac{\frac{1}{n} \frac{1}{n - 1}}{n!}$$
Sum((1/(n*(n - 1)))/factorial(n), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{\frac{1}{n} \frac{1}{n - 1}}{n!}$$
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
$$a_{n} = \frac{1}{n \left(n - 1\right) n!}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\left(n + 1\right) \left|{\frac{\left(n + 1\right)!}{\left(n - 1\right) n!}}\right|\right)$$
Let's take the limit
we find
$$\frac{\frac{1}{n} \frac{1}{n - 1}}{n!}$$
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
$$a_{n} = \frac{1}{n \left(n - 1\right) n!}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\left(n + 1\right) \left|{\frac{\left(n + 1\right)!}{\left(n - 1\right) n!}}\right|\right)$$
Let's take the limit
we find
False
False
The rate of convergence of the power series
Numerical answer
[src]
Sum((1/(n*(n - 1)))/factorial(n), (n, 1, oo))
Sum((1/(n*(n - 1)))/factorial(n), (n, 1, oo))
The graph
Examples of finding the sum of a series
- The Sum of the Power Series
x^n/n
(x-1)^n
- Factorial
1/2^(n!)
n^2/n!
x^n/n!
k!/(n!*(n+k)!)
- Flint Hills Series
csc(n)^2/n^3
- Basel problem
1/n^2
1/n^4
1/n^6
- Harmonic series
1/n
- Grandi's series
(-1)^n
- Alternating series
(-1)^(n + 1)/n
(n + 2)*(-1)^(n - 1)
(3*n - 1)/(-5)^n
(-1)^(n - 1)*n/(6*n - 5)
- Newton–Mercator series
(-1)^(n + 1)/n*x^n
- Exam the series for convergence
(3*n - 1)/(-5)^n