Finding Cluster Points/Accumulation Points

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SUMMARY

The set of cluster points for the sequence A := {(−1)n/n : n ∈ N} is confirmed to be solely 0. This conclusion is reached by applying the definition of a cluster point, which states that a point x is a cluster point of a set if every neighborhood of x contains at least one point from the set different from x itself. In this case, as n approaches infinity, the terms of the sequence oscillate between positive and negative values, converging to 0, thus establishing it as the only cluster point.

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  • Understanding of sequences and limits in real analysis
  • Familiarity with the definition of cluster points
  • Basic knowledge of mathematical proofs
  • Experience with oscillating sequences
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  • Study the definition and properties of cluster points in topology
  • Learn about convergence of sequences and their limits
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  • Practice constructing proofs for identifying cluster points in various sets
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brooklysuse
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Find the set of cluster points for the set A := {(−1)n/n : n ∈ N}. Justify your answer with
proof.

I believe 0 is a cluster point but I can't figure out how to prove this, or how to prove any other point is not.

Any quick help would be appreciated. Thanks.
 
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brooklysuse said:
Find the set of cluster points for the set A := {(−1)n/n : n ∈ N}.
I believe 0 is a cluster point
Hmm, I believe $$\frac{(-1)n}{n}=-1$$.
 
brooklysuse said:
Find the set of cluster points for the set A := {(−1)n/n : n ∈ N}. Justify your answer with
proof.

I believe 0 is a cluster point but I can't figure out how to prove this, or how to prove any other point is not.

Any quick help would be appreciated. Thanks.
I guess you mean $A := \{(−1)^n/n : n \in \Bbb{N}\}$. You are correct that $0$ is the only cluster point. To prove it, you will need to use the definition of a cluster point, which is ... ? (Start from there.)
 

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