Prove cauchy sequence and thus convergence

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SUMMARY

The sequence (Xn) defined by the condition |Xn+1 - Xn| ≤ λ^n r, where r > 0 and λ is in the interval (0, 1), is proven to be a Cauchy sequence, thereby establishing its convergence. The proof utilizes two key facts: for every ε > 0, there exists a natural number N such that λ^N r < ε, and the triangle inequality. This confirms that the sequence converges as it satisfies the Cauchy criterion.

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  • Understanding of Cauchy sequences
  • Familiarity with convergence in real analysis
  • Knowledge of the triangle inequality
  • Basic concepts of limits and sequences
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  • Explore the implications of convergence in metric spaces
  • Learn about the triangle inequality and its applications in proofs
  • Investigate sequences and series in real analysis
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manooba
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Let (Xn) be a sequence satisfying

|Xn+1-Xn| ≤ λ^n r

Where r>0 and λ lies between (0,1). Prove that (Xn) is a Cauchy sequence and so is convergent.
 
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I have a hunch that you could use two facts:

1) for every ε > 0 there exists some natural number N such that λ^N r < ε
2) the triangle inequality
 
manooba said:
Let (Xn) be a sequence satisfying

|Xn+1-Xn| ≤ λ^n r

Where r>0 and λ lies between (0,1). Prove that (Xn) is a Cauchy sequence and so is convergent.

I posted the solution of that with r=1 in a similar thread called cauchy sequence problem
 

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