What Is the Interval of Convergence for the Given Series?

In summary, the interval of convergence is a mathematical concept used to determine the range of values for which a power series will converge. It can be determined by using the ratio test or the root test, and if the limit is equal to 1, other methods may need to be used. The interval of convergence can be infinite and understanding it is important in many fields of study.
  • #1
Ki-nana18
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Homework Statement


The summation from n=1 to infinity of ((n!)x^(2n))/((2n-1)!) Find the Interval of Convergence of this series.


Homework Equations


Ratio test


The Attempt at a Solution


I applied the ratio test, then got x^2 times the limit as n approaches infinity of (n+1)/(2n(2n+1)). I took the limit and got zero and since 0<1 the series converges. Does this mean the interval of convergence is (-infinity,+infinity)?
 
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  • #2
Yes, the limit of the ratio is zero. So that's exactly what it means. The interval of convergence is (-infinity,infinity).
 

Related to What Is the Interval of Convergence for the Given Series?

What is the interval of convergence?

The interval of convergence is a mathematical concept used in the study of power series. It refers to the range of values for which a power series will converge, or approach a finite value.

How is the interval of convergence determined?

The interval of convergence can be determined by using the ratio test or the root test. These tests involve evaluating the limit of the ratio or the root of the terms in the series. If the limit is less than 1, the series will converge within that interval.

What happens if the limit is equal to 1?

If the limit is equal to 1, the test is inconclusive and other methods, such as the alternating series test, may need to be used to determine convergence.

Can the interval of convergence be infinite?

Yes, the interval of convergence can be infinite, meaning the series will converge for all values of the variable. This is often the case for simple power series such as geometric series.

Why is the interval of convergence important?

The interval of convergence is important because it determines the range of values for which a power series can be used to approximate a function. Understanding the interval of convergence is essential in many areas of mathematics, physics, and engineering.

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