Mister Exam

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Sum of series:
1/(n*(n+1)*(n+2))
1/n^4
factorial(n)*3^n/n^n
ln(1-(1/n^2))
Identical expressions
one /n^ four
1 divide by n to the power of 4
one divide by n to the power of four
1/n4
1/n⁴
1 divide by n^4

Sum of series/ 1/n^4

Sum of series 1/n^4

The solution

You have entered [src]

  oo    
____    
\   `   
 \    1 
  \   --
  /    4
 /    n 
/___,   
n = 1

$$\sum_{n=1}^{\infty} \frac{1}{n^{4}}$$

Sum(1/(n^4), (n, 1, oo))

The radius of convergence of the power series

Given number:
$$\frac{1}{n^{4}}$$
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
$$a_{n} = \frac{1}{n^{4}}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left(n + 1\right)^{4}}{n^{4}}\right)$$
Let's take the limit
we find

True

False

The rate of convergence of the power series

The answer [src]

  4
pi 
---
 90

$$\frac{\pi^{4}}{90}$$

pi^4/90

Numerical answer [src]

1.08232323371113819151600369654

1.08232323371113819151600369654

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
```

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Identical expressions

Sum of series 1/n^4

The solution

Examples of finding the sum of a series