Convergence of Alternating Series: ln(1+x) <= x Hint for Absolute Convergence

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In summary, the given equation is an alternating series and each term gets smaller and smaller, converging to zero. The ratio test also confirms that it is absolutely convergent. The hint given is to show that ln(1 + x) <= x if x > 0, which can help establish one of the conditions for the Leibniz test, where the terms are getting smaller.
  • #1
rcmango
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Homework Statement



Does this problem converge absolutely, conditionally, or does it diverge?

the equation: [/URL]

Homework Equations



also, the hint is to first show that ln(1 + x) <= x if x > 0

The Attempt at a Solution



It looks like an alternating series. not sure what the hint is implying or if its converging.

Thanks for any help.
 
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  • #2
Each term gets smaller and smaller, and converges to zero. It is absolutely convergent.

The ratio test will tell you it converges as well.
 
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  • #3
Gibz said:
Each term gets smaller and smaller, and converges to zero. It is absolutely convergent.
Is that what you mean to say? Each term of
[tex]\Sigma_{n\rightarrow \infty}\frac{1}{n}[/itex]
"gets smaller and smaller, and converges to zero" but the series doesn't converge at all.
 
  • #4
when it is an alternating series you can use Leibniz test
your pic is not very clear... but my guess is that the hint is to help you establish one of the condition in the Leibniz test namely, the terms are getting smaller

Leibniz test:
If [tex]\sum_1^{\infty} (-1)^{n+1} b_n[/tex] such that all [tex]b_n>0[/tex] (ie alternating series) and [tex]b_{n+1} < b_n\; \forall\,n[/tex] and [tex]b_n\rightarrow 0[/tex], then series converges to S and [tex]|S-S_k|\leq b_{k+1}[/tex]
 

FAQ: Convergence of Alternating Series: ln(1+x) <= x Hint for Absolute Convergence

What is the definition of a convergent alternating series?

A convergent alternating series is a series in which the terms alternate in sign and decrease in magnitude, eventually approaching zero, and the sum of the series approaches a finite limit.

How can I determine if a series is absolutely convergent?

A series is absolutely convergent if the sum of the absolute values of its terms is finite. In other words, if the absolute values of the terms form a convergent series.

What is the hint for proving absolute convergence in the series ln(1+x) <= x?

The hint for proving absolute convergence in this series is to use the comparison test. This involves finding a simpler series with known convergence properties that is greater than or equal to the given series.

Why is the ln(1+x) series considered an alternating series?

This series is considered an alternating series because the signs of its terms alternate between positive and negative, and the terms decrease in magnitude as x increases.

How can I use the hint to prove absolute convergence in the ln(1+x) series?

Using the hint, we can compare the given series with the series 1/x. Since 1/x is a convergent series for x > 0, and ln(1+x) <= x for all x > 0, this shows that the given series is absolutely convergent for all x > 0.

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