Proving Convergence of Two Sums at 0

In summary, the conversation is discussing the convergence of two given sums: e^(n^2)*x^n and e*n^(n)*x^(n). The discussion mentions the ratio test for power series and asks for the values of An+1/An for these series. It is also mentioned that the series only converge at x=0 and the question of how to write the power series for these exponential functions is raised.
  • #1
tbone413
7
0

Homework Statement


Prove that the following sums only converge at 0.
sum of: e^(n^2)*x^n , and
sum of: e*n^(n)*x^(n)


Homework Equations


well i know series converge if the lim as n approaches inf of the abs(x-c) is less than (An/An+1) but I have no idea how to prove it, I saw these for the first time yesterday in class, and don't know much about it.


The Attempt at a Solution

 
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  • #2
Whart you are talking about is the "ratio test" for power series. What is An+1/An for these series?
 
  • #3
tbone413 said:

Homework Statement


Prove that the following sums only converge at 0.
sum of: e^(n^2)*x^n , and
sum of: e*n^(n)*x^(n)

Are you missing either division signs or negative signs in exponents somewhere? I don't see how these are going to converge to zero as you've written them...
 
  • #4
dynamicsolo said:
Are you missing either division signs or negative signs in exponents somewhere? I don't see how these are going to converge to zero as you've written them...
He didn't say they converge to 0, he said they only converge at x= 0.
 
  • #5
HallsofIvy said:
He didn't say they converge to 0, he said they only converge at x= 0.

Sorry, missed the 'only'; I've read too many sentences with wrong prepositions lately and thought the OP meant 'to'. (Your mentioning the Ratio Test reinforced this...)

The first question might be: how do you write the power series for these exponential functions? What do you get when you multiply them by x^n?
 

Related to Proving Convergence of Two Sums at 0

1. What is "convergence" in terms of sums?

Convergence refers to the behavior of a series or sequence as its terms are added together. In the context of sums at 0, convergence means that the sum approaches a specific value as the number of terms increases.

2. How is convergence of two sums at 0 proven?

Convergence of two sums at 0 can be proven using mathematical techniques such as the limit comparison test, the ratio test, or the root test. These methods involve evaluating the behavior of the sums as the number of terms increases and determining if they approach a specific value or not.

3. What is the significance of proving convergence of two sums at 0?

Proving convergence of two sums at 0 is important in mathematics and science as it allows us to make accurate predictions and calculations. It also helps us understand the behavior of series and sequences and their relationship to real-world phenomena.

4. Can two sums at 0 converge to different values?

No, if two sums at 0 converge, they must converge to the same value. This is because the behavior of the sums as the number of terms increases will be the same, and they will approach the same value.

5. What are some real-world applications of proving convergence of two sums at 0?

Proving convergence of two sums at 0 has practical applications in fields such as physics, engineering, and economics. It is used to analyze and predict the behavior of systems and processes that involve series and sequences, such as population growth, financial investments, and signal processing.

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