Radius of Convergence for Ratio Test in Calculus Questions

In summary, the conversation discusses the process of checking the interval of convergence using the ratio test. It is suggested to substitute the values -2 and 2 into the original equation to determine if they are convergent or divergent. It is also mentioned that there may be a typo in the problem statement.
  • #1
belvol16
9
0

Homework Statement


problem 9.PNG


Homework Equations


Ratio test.

The Attempt at a Solution


work 9.PNG
[/B]
I guess I'm now uncertain how to check my interval of convergence (whether the interval contains -2 and 2)...I've been having troubles with this in all of the problems given to me. Do I substitute -2 back into the original equation and see if it is convergent or divergent?
 
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  • #2
belvol16 said:

Homework Statement


View attachment 110223

Homework Equations


Ratio test.

The Attempt at a Solution


View attachment 110224 [/B]
I guess I'm now uncertain how to check my interval of convergence (whether the interval contains -2 and 2)...I've been having troubles with this in all of the problems given to me. Do I substitute -2 back into the original equation and see if it is convergent or divergent?

Yes, you have to check ##x= \pm2## explicitly.
 
  • #3
belvol16 said:

Homework Statement


View attachment 110223

Homework Equations


Ratio test.

The Attempt at a Solution


View attachment 110224[/B]

Either your work's wrong or there's a typo in the problem statement. Look at the exponent of ##x##.
 

What is the radius of convergence?

The radius of convergence is a mathematical concept that is used to determine the interval of values for which a power series converges. It is denoted by R and can be calculated using the ratio test.

How is the radius of convergence calculated?

The radius of convergence can be calculated using the ratio test. This involves taking the limit of the absolute value of the ratio of consecutive terms in the power series as n approaches infinity. If the limit is less than 1, the series converges. The radius of convergence is then equal to the reciprocal of this limit.

What does the radius of convergence tell us?

The radius of convergence tells us the interval of values for which the power series will converge. If a value falls within this interval, the series will converge to a specific value. If it falls outside of this interval, the series will either diverge or oscillate.

What factors affect the radius of convergence?

The radius of convergence can be affected by the coefficients in the power series. If the coefficients have a pattern or follow a specific sequence, the radius of convergence may be larger. Additionally, the radius of convergence can also be affected by the function being approximated by the power series.

Why is the radius of convergence important?

The radius of convergence is important because it allows us to determine the interval of convergence for a power series. This helps us understand the behavior of the series and whether it will provide a good approximation for the function being studied. It also allows us to determine the accuracy of the approximation within the interval of convergence.

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