Convergence and Divergence of a Series

In summary, convergence and divergence of a series refers to the behavior of its limit as the number of terms increases. A series that converges has a definite limit, while a series that diverges does not. A series can diverge by either approaching infinity or by not approaching any specific value.
  • #1
bmed90
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Currently, we are covering the topic of convergence and divergence of a series in my calculus 2 class. I was wondering if you could give me in there own words what it means for a series to converge, and what it means for a series to diverge.
I know that when a series converges, its limit reaches a definite value, and when it converges its limit is indefinite (infinity). However that right there is all I know of convergence and divergence. I am really trying to learn the concept behind convergence and divergence. If anyone would be willing to enlighten me with their own explanation of convergence and divergence it would be appreciated. Preferably in a more literal sense, rather than a mathematical explanation.
 
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  • #2
Saying that a series "converges" essentially means that, even though it contains an infinite number of terms, it has a "sum". (I am assuming that you really do mean "series" and not "sequence".) A series might diverge (not have a finite sum) because it is gets larger and larger ("goes to infinity"). But it is possible for a series to diverge even though it does NOT "go to infinity". For example, [itex]\sum_{n=0}^\infty (-1)^n= 1- 1+ 1- 1+ \cdot\cdot\cdot[/itex] diverges because its "partial sums", 1, 1- 1= 0, 1- 1+ 1= 1, 1- 1+ 1- 1= 0, ..., alternate between 0 and 1 and do not approach a single value.
 

What is the definition of convergence and divergence of a series?

Convergence and divergence of a series refers to the behavior of a sequence of numbers when they are added up. A series is said to converge if the sum of its terms approaches a finite value as the number of terms increases, and it is said to diverge if the sum of its terms approaches infinity or does not approach any finite value.

How can I determine if a series is convergent or divergent?

There are several tests that can be used to determine the convergence or divergence of a series, such as the divergence test, comparison test, ratio test, and integral test. These tests involve analyzing the behavior of the terms in the series and can help determine if the series will converge or diverge.

What is the difference between absolute and conditional convergence of a series?

Absolute convergence refers to a series in which the sum of the absolute values of its terms converges. This means that even if the signs of the terms are changed, the series will still converge. On the other hand, conditional convergence refers to a series in which the sum of the terms converges, but if the signs of the terms are changed, the series will diverge.

Can a series be both convergent and divergent?

No, a series cannot be both convergent and divergent. A series can only have one of these two behaviors. If the sum of the terms approaches a finite value, the series is convergent. If the sum of the terms approaches infinity or does not approach any finite value, the series is divergent.

Why is it important to understand the convergence and divergence of a series?

Understanding the convergence and divergence of a series is important in many areas of mathematics and science. It can help in determining the behavior of functions, evaluating integrals, solving differential equations, and in other applications. It is also essential in analyzing the accuracy and limitations of numerical methods and algorithms.

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