Mister Exam
Other calculators
- Taylor Series Step by Step
- Fourier series step by step
- Differential equations Step by Step
- Product of series
-
How to use it?
- Sum of series:
-
2^n/n^2
-
(n-1)/2^(n+1)
-
2^(2*n-1)/9^n
-
1/4^1
-
Identical expressions
- one /((two *n+ one)(two *n+ five))
- 1 divide by ((2 multiply by n plus 1)(2 multiply by n plus 5))
- one divide by ((two multiply by n plus one)(two multiply by n plus five))
- 1/((2n+1)(2n+5))
- 1/2n+12n+5
- 1 divide by ((2*n+1)(2*n+5))
-
Similar expressions
- 1/((2*n+1)(2*n-5))
- 1/((2*n-1)(2*n+5))
Sum of series 1/((2*n+1)(2*n+5))
The solution
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oo ___ \ ` \ 1 ) ------------------- / (2*n + 1)*(2*n + 5) /__, n = 1
$$\sum_{n=1}^{\infty} \frac{1}{\left(2 n + 1\right) \left(2 n + 5\right)}$$
Sum(1/((2*n + 1)*(2*n + 5)), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{1}{\left(2 n + 1\right) \left(2 n + 5\right)}$$
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
$$a_{n} = \frac{1}{\left(2 n + 1\right) \left(2 n + 5\right)}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left(2 n + 3\right) \left(2 n + 7\right)}{\left(2 n + 1\right) \left(2 n + 5\right)}\right)$$
Let's take the limit
we find
$$\frac{1}{\left(2 n + 1\right) \left(2 n + 5\right)}$$
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
$$a_{n} = \frac{1}{\left(2 n + 1\right) \left(2 n + 5\right)}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left(2 n + 3\right) \left(2 n + 7\right)}{\left(2 n + 1\right) \left(2 n + 5\right)}\right)$$
Let's take the limit
we find
True
False
The rate of convergence of the power series
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