Mister Exam

### Other calculators

• #### How to use it?

• Sum of series:
• 1\3^n
• x^(4n)/n!
• 1/n*(n+1)(n+2)
• nx^n
• #### Identical expressions

• one \ three ^n
• 1\3 to the power of n
• one \ three to the power of n
• 1\3n

# Sum of series 1\3^n

=

### The solution

You have entered [src]
  oo
___
\
\    -n
/   3
/__,
n = 1    
$$\sum_{n=1}^{\infty} \left(\frac{1}{3}\right)^{n}$$
Sum((1/3)^n, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\left(\frac{1}{3}\right)^{n}$$
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
$$a_{n} = 1$$
and
$$x_{0} = -3$$
,
$$d = -1$$
,
$$c = 0$$
then
$$\frac{1}{R} = \tilde{\infty} \left(-3 + \lim_{n \to \infty} 1\right)$$
Let's take the limit
we find
False

$$R = 0$$
The rate of convergence of the power series
1/2
$$\frac{1}{2}$$
1/2
0.500000000000000000000000000000
0.500000000000000000000000000000`