Convergence of Infinite Sums and Limits: A L'Hopital's Rule Perspective

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In summary, the limit of a sum is the value that a sum approaches as the number of terms in the sum gets larger and larger. It is calculated by evaluating the individual limits of each term and adding them together. The limit can be infinite if the terms in the sum increase without bound. The sum of limits is equal to the sum of the individual limits of each term, but may not always equal the limit of the sum. The order of terms does not affect the limit of a sum, unless the terms are infinite.
  • #1
Apteronotus
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For an infinite sum, is the limit of the sum = sum of the limit?
ie.
[tex]
lim_{x \rightarrow a} \sum_{n=0}^\infty f(x,n)= \sum_{n=0}^\infty lim_{x \rightarrow a}f(x,n)
[/tex]
 
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  • #2
I'm fairly certain that it's true if and only if
[tex]
\sum_{n=0}^{\infty} f(x,n)
[/tex]

converges uniformly. In general, however, no.
 
  • #3
Thank you L'Hopital!
 

1. What is the limit of a sum?

The limit of a sum is the value that a sum approaches as the number of terms in the sum gets larger and larger. It is denoted by the symbol "lim" and is used to describe the behavior of a function as the input values approach a specific value.

2. How is the limit of a sum calculated?

The limit of a sum is calculated by evaluating the individual limits of each term in the sum and then adding them together. This is based on the fact that the limit of a sum is equal to the sum of the limits.

3. Can the limit of a sum be infinite?

Yes, the limit of a sum can be infinite if the terms in the sum increase without bound. In this case, the sum is said to diverge and the limit is said to be infinite.

4. What is the sum of limits?

The sum of limits is the sum of the individual limits of each term in a sum. This is based on the fact that the limit of a sum is equal to the sum of the limits. However, it is important to note that the sum of limits does not always equal the limit of the sum.

5. How does the order of terms affect the limit of a sum?

The order of terms does not affect the limit of a sum as long as the terms are finite. This is because the limit of a sum is based on the individual limits of each term, which are not affected by the order in which they are added. However, if the terms are infinite, the order can affect the limit of the sum.

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