Summing an Infinite Series: Can We Prove Divergence?

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Discussion Overview

The discussion centers around the divergence of the infinite series 1 + (1/2) + (1/3) + (1/4) + ... + (1/n). Participants explore methods to prove its divergence and examine the validity of the integral test in this context.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant asks whether the series can be proven to be divergent and requests an expression for the sum to infinity in terms of n.
  • Another participant suggests replacing the series with a smaller divergent series or using the integral test as a method of proof.
  • A different participant expresses doubt about the validity of the integral test, questioning its applicability due to the discontinuity of the graph of 1/n.
  • In response, another participant asserts that the integral test is a valid approach to prove the divergence of the series.
  • A later post reiterates the original question about proving divergence and presents a manipulation of the series, suggesting that the sum of certain terms leads to a repeated value, questioning if this is sufficient for proof.

Areas of Agreement / Disagreement

Participants express differing views on the validity of the integral test for proving divergence, indicating a lack of consensus on this method. The overall discussion remains unresolved regarding the proof of divergence.

Contextual Notes

There are limitations regarding the assumptions made about the applicability of the integral test and the continuity of the function involved. The manipulation of the series presented in the later post also leaves open questions about its sufficiency as a proof.

Fookie
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1+(1/2)+(1/3)+(1/4)+(1/5)...+(1/n)

can sum one prove this series is divergent?



or just tell me what the expression for sum to infintiy in terms of n is?
 
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replace with a strictly smaller divergent series eg 1+1/2+1/4+1/4+1/8+1/8+1/8+1/8+1/16... or use the integral test.
 
but i thot that the integral test is not valid for series coz the graph of 1/n will not be contiuous :eek:
 
I think you ought to look up the integral test and see what it says. The integral test is a perfectly valid way to prove this result.
 
Fookie said:
1+(1/2)+(1/3)+(1/4)+(1/5)...+(1/n)

can sum one prove this series is divergent?

Forget the first term (1), and observe that:

1/2+1/3 + 1/4+1/5+1/6+1/7 + 1/8+1/9+1/10+1/11+1/12+1/13+1/14+1/15 +...>

2*1/4 + 4*1/8 + 8*1/16 +... =

1/2 + 1/2 + 1/2 +...


Is it enough ?
 

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