Proving convergence of Sequence dependent on previous terms

In summary, the sequence (xn) defined by xn+1 = (2009xn + 2010)/2011 for n > 1 converges and its limit can be found using the Monotone Convergence Theorem. To prove monotonicity, the nth term minus (n+1)th term should be analyzed in terms of the nth term, which also gives a clue about the limit.
  • #1
tallandpoofy
1
0

Homework Statement



Let x1 > 9000, and

xn+1 = )2009xn + 2010)/2011 for n >1

show that (xn) converges and find its limit


Homework Equations



Definition of a limit, Monotone Convergence Theorem.

The Attempt at a Solution



Since xn+1 is monotone for n>1 and bounded, then it converges by Monotone Convergence Theorem.

How do i prove monotone for this function?
I tried xn+2 - xn+1 < 0 but it does not work since xn+1 is dependent on xn
 
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  • #2
tallandpoofy said:

Homework Statement



Let x1 > 9000, and

xn+1 = )2009xn + 2010)/2011 for n >1

show that (xn) converges and find its limit


Homework Equations



Definition of a limit, Monotone Convergence Theorem.

The Attempt at a Solution



Since xn+1 is monotone for n>1 and bounded, then it converges by Monotone Convergence Theorem.

How do i prove monotone for this function?
I tried xn+2 - xn+1 < 0 but it does not work since xn+1 is dependent on xn

You should be able to use your approach to prove monotonicity. Compute nth term minus (n+1)th term in terms of nth term (equivalent to your suggestion). Then analyze under what conditions it is positive (meaning sequence is monotonically decreasing). This analysis should also give you a clue about the limit.
 

Related to Proving convergence of Sequence dependent on previous terms

1. What does it mean for a sequence to converge?

A sequence is said to converge if its terms become closer and closer to a single value as the index (or term number) increases. In other words, the terms of the sequence eventually approach a specific limit.

2. How do you prove convergence of a sequence?

To prove convergence of a sequence, you must show that the terms of the sequence get arbitrarily close to a specific limit value. This can be done by using a variety of techniques such as the squeeze theorem, the ratio test, or the root test.

3. What is a sequence dependent on previous terms?

A sequence dependent on previous terms is a sequence where each term is determined by the previous terms in the sequence. This means that the value of each term is not independent and is affected by the values of the previous terms.

4. Why is proving convergence of a sequence dependent on previous terms important?

Proving convergence of a sequence dependent on previous terms is important because it allows us to understand the behavior of the sequence and determine if it will eventually approach a specific limit. This can have applications in various fields such as physics, engineering, and economics.

5. What are some common techniques used to prove convergence of a sequence dependent on previous terms?

Some common techniques used to prove convergence of a sequence dependent on previous terms include the monotone convergence theorem, the Cauchy criterion, and the Bolzano-Weierstrass theorem. These techniques involve analyzing the behavior and properties of the sequence to determine if it converges to a specific limit.

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