A sequence an is called a cauchy sequence if for every

Question

Question:

Definition of a Cauchy Sequence: 

A sequence (a_n) is called a Cauchy sequence if, for every ε > 0, there exists an N ∈ natural number such that whenever m,n ≥ N it follows that |a_n - a_m| < ε.

Sn = (-1)ⁿ/n. For all n in natural number

Prove that the given sequence: S_n is a Cauchy sequence by using DEFINITION.