Proving the Circle Property of Infinite Sequence in Complex Analysis

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Homework Help Overview

The discussion revolves around proving that the infinite sequence defined by the product \( a_{n}= \prod_{k}^\infty (1 + \frac{i}{k}) \) consists of points on a circle in the context of complex analysis.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the need to demonstrate that the infinite product converges to a finite limit, which would imply a finite radius for the points on the circle. There are suggestions to analyze the series derived from the product and to consider the implications of writing terms in pairs.

Discussion Status

Some participants have offered hints regarding the structure of the series and the relationship between the terms, while others have acknowledged the need to establish the convergence of the product. Multiple lines of reasoning are being explored without a clear consensus on the approach.

Contextual Notes

Participants note the challenge of working with infinite products and series in the complex plane, as well as the implications of the argument of the sequence covering the entire circle.

raopeng
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Homework Statement


To prove that the sequence [itex]a_{n}= \prod_{k}^\infty (1 + \frac{i}{k})[/itex] when n is infinite constitutes points on a circle.

Homework Equations


Ehh no idea what equations shall be used.

The Attempt at a Solution


A friend asked me this, but I am usually engaged more with the physical aspects of Complex Analysis... so I have no idea how I should approach this question.
 
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Well points on a circle have a particular (finite) radius.

So you need to prove your infinite product has a finite limit,
Since we are in the complex plane this will be a radius, as every point with this modulus will be included.
 
Thank you. Yes I noticed that too, as we can extract an infinite series from it...
 
So what happens if you write a few of the terms of the series out and multiply them in pairs?

Further hint put 1/k = α.
So the terms take the form (1+αi)
 
Thank you for the help. Also [itex]arg a_{n} = \sum^{\inf}_{k}\frac{1}{k}[/itex] covers the entire circle.
 

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