Decide whether or not the given sequence converges to a limit. If it does not, find, in each case, at least one convergent subsequence. We suppose n= 1, 2, 3,... xn = (-1)n(1-(1/n))

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
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Decide whether or not the given sequence converges to a limit. If it does not, find, in each case, at least one convergent subsequence. We suppose n= 1, 2, 3,...

xn = (-1)n(1-(1/n))

 

Expert Solution
Step 1: step 1

To determine whether the given sequence x subscript n equals not stretchy left parenthesis negative 1 not stretchy right parenthesis to the power of n not stretchy left parenthesis 1 minus 1 over n not stretchy right parenthesis converges to a limit or not, we can analyze its behavior.

Let's consider the sequence for different values of n:

- For n = 1: x subscript 1 equals not stretchy left parenthesis negative 1 not stretchy right parenthesis to the power of 1 not stretchy left parenthesis 1 minus 1 over 1 not stretchy right parenthesis equals negative 1 not stretchy left parenthesis 1 minus 1 not stretchy right parenthesis equals negative 1
- For n = 2: x subscript 2 equals not stretchy left parenthesis negative 1 not stretchy right parenthesis squared not stretchy left parenthesis 1 minus 1 half not stretchy right parenthesis equals 1 not stretchy left parenthesis 1 minus 0.5 not stretchy right parenthesis equals 0.5
- For n = 3: x subscript 3 equals not stretchy left parenthesis negative 1 not stretchy right parenthesis cubed not stretchy left parenthesis 1 minus 1 third not stretchy right parenthesis equals negative 1 not stretchy left parenthesis 1 minus 0.3333 not stretchy right parenthesis almost equal to negative 0.6667
- For n = 4: x subscript 4 equals not stretchy left parenthesis negative 1 not stretchy right parenthesis to the power of 4 not stretchy left parenthesis 1 minus 1 fourth not stretchy right parenthesis equals 1 not stretchy left parenthesis 1 minus 0.25 not stretchy right parenthesis equals 0.75

It appears that the sequence alternates between positive and negative values and that the absolute values of the terms are approaching 0 as n increases. However, the sequence does not converge to a single limit because it oscillates between positive and negative values indefinitely.


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