Mister Exam
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How to use it?
- Sum of series:
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(3^n+5^n)/15^n
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-1^(n-1)/((2*n-1)*3^(n-1))
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2^(1.5*n)*0.5^(n-1)*0.5^(n)
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1/5^n
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Identical expressions
- (three ^n+ five ^n)/ fifteen ^n
- (3 to the power of n plus 5 to the power of n) divide by 15 to the power of n
- (three to the power of n plus five to the power of n) divide by fifteen to the power of n
- (3n+5n)/15n
- 3n+5n/15n
- 3^n+5^n/15^n
- (3^n+5^n) divide by 15^n
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Similar expressions
- (3^n-5^n)/15^n
Sum of series (3^n+5^n)/15^n
The solution
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oo ____ \ ` \ n n \ 3 + 5 ) ------- / n / 15 /___, n = 1
$$\sum_{n=1}^{\infty} \frac{3^{n} + 5^{n}}{15^{n}}$$
Sum((3^n + 5^n)/15^n, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{3^{n} + 5^{n}}{15^{n}}$$
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
$$a_{n} = 3^{n} + 5^{n}$$
and
$$x_{0} = -15$$
,
$$d = -1$$
,
$$c = 0$$
then
$$\frac{1}{R} = \tilde{\infty} \left(-15 + \lim_{n \to \infty}\left(\frac{3^{n} + 5^{n}}{3^{n + 1} + 5^{n + 1}}\right)\right)$$
Let's take the limit
we find
$$R = 0$$
$$\frac{3^{n} + 5^{n}}{15^{n}}$$
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
$$a_{n} = 3^{n} + 5^{n}$$
and
$$x_{0} = -15$$
,
$$d = -1$$
,
$$c = 0$$
then
$$\frac{1}{R} = \tilde{\infty} \left(-15 + \lim_{n \to \infty}\left(\frac{3^{n} + 5^{n}}{3^{n + 1} + 5^{n + 1}}\right)\right)$$
Let's take the limit
we find
False
False
$$R = 0$$
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