Convergence - Divergence of a Series

In summary, the given series is an alternating series with terms of the form (-1)^n * n/(n+2). The series will diverge as n approaches infinity, as the limit of the terms is 1 and the alternating series test states that a series will converge only if the terms approach 0. Therefore, the given series will not converge.
  • #1
remaan
132
0

Homework Statement


Test the series for convergence or divergence
-1/3+ 2/4 - 3/5 +4/6 - 5/7 + ....


Homework Equations



I think it's an alternating series

The Attempt at a Solution



I found that an = (-1) ^n * n/ (n+2)

And it approaches 1 as n goes to inifty so the series will Diverge

Is that right ??
 
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  • #2
hmmm.
alternating series test says that if you can identify a series of the form [itex]\sum (-1)^n a_n[/itex] and the [itex]a_n[/itex] are positive and decreasing such that [itex]a_n \rightarrow 0[/itex] then [itex]\sum (-1)^n a_n[/itex] will converge.

so here you have [itex]a_n=\frac{n}{n+2}=\frac{1}{1+\frac{2}{n}}[/itex]

how does this behave as [itex]n \rightarrow \infty[/itex]
 
  • #3
It will approach 1. and the series will Diverge.

What do you think ?
 

FAQ: Convergence - Divergence of a Series

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

Convergence of a series refers to the behavior of the terms in the series as the number of terms goes to infinity. A series is said to converge if the terms approach a finite limit. On the other hand, divergence of a series occurs when the terms do not approach a finite limit as the number of terms increases.

How do you test for convergence or divergence of a series?

There are several methods for testing convergence or divergence of a series, including the divergence test, comparison test, ratio test, and integral test. These methods involve comparing the given series to another known series or using mathematical operations to determine the behavior of the terms.

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

The convergence or divergence of a series tells us whether the terms in the series become infinitely large or approach a finite limit. This information is important in determining the behavior and characteristics of a series, as well as its applications in fields such as mathematics, physics, and engineering.

What is meant by absolute and conditional convergence of a series?

A series is said to have absolute convergence if the series of absolute values of its terms converges. On the other hand, conditional convergence occurs when the series converges, but the series of absolute values of its terms diverges. In other words, for conditional convergence, the series must be rearranged in a specific order to converge.

Can a series be both convergent and divergent?

No, a series cannot be both convergent and divergent. A series can either converge or diverge, depending on the behavior of its terms. However, it is possible for a series to have both convergent and divergent subsequences, which can occur in alternating series or series with oscillating terms.

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