What Are the Properties of the Sequence (Xn)?

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Homework Help Overview

The problem involves analyzing a sequence defined recursively, with the first term given as X1=1 and subsequent terms defined by Xn+1=1/(3+Xn) for n≥2. Participants are tasked with proving the convergence of the sequence and identifying its limit.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster considers using the monotone convergence theorem but is uncertain about proving the sequence's monotonicity and boundedness. Some participants suggest generating initial terms of the sequence to analyze its behavior, while others question the relationship between terms and propose examining subsequences.

Discussion Status

The discussion is ongoing, with participants exploring different aspects of the sequence's behavior. There is an acknowledgment of the sequence's non-monotonic behavior based on the generated terms, and suggestions have been made to investigate the relationships between terms further.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can share or the methods they can use. The original poster has not yet established whether the sequence is bounded or monotonic, which are critical to applying the monotone convergence theorem.

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Homework Statement


let (Xn) be a sequence in R given by X1=1 and Xn+1=1/(3+Xn) for n>=2. prove Xn converges and find the limit.


Homework Equations





The Attempt at a Solution


well i think using the monotone convergence theorem would help but i would have to prove that the sequence is bounded and monotone. But I have not been able to prove it is monotone yet.
 
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Show us your work so we can help you.

Sometimes it helps to generate the first few terms of a sequence.
 
X2=1/4, X3=4/13, X4=13/43, X5=43/142... the sequence kinda flips up and down. it will go down, up, down,... it does not seem monotone...
 
How is xn+2 related to xn ?

Then look at the subsequences, (x2n) and (x2n+1).
 

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