Question
Download Solution PDFIf {xn} is a convergent sequence in ℝ and {yn} is a bounded sequence in ℝ, then we can conclude that
- {xn + yn} is convergent
- {xn + yn} is bounded
- {xn + yn} has no convergent subsequence
- {xn + yn} has no bounded subsequence
Answer (Detailed Solution Below)
Option 2 : {xn + yn} is bounded
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Detailed Solution
Download Solution PDFConcept:
(i) Every convergent sequence is bounded.
Explanation:
{xn} is a convergent sequence in ℝ. So it is bounded.
Then there exists a real number M such that |xn| ≤ M.
{yn} is a bounded sequence in ℝ
Then there exists a real number L such that |yn| ≤ L.
Now, |xn + yn| ≤ |xn| + |yn| ≤ M + L
So, {xn + yn} is bounded.
Option (2) is true.
Let {xn} = {\(\frac1n\)} and {yn} = {(-1)n} then {xn} is a convergent sequence in ℝ and {yn} is a bounded sequence in ℝ.
But {xn + yn} = {\(\frac1n\) + (-1)n} which is not convergent and it has convergent and bounded subsequence.
Options (1), (3) and (4) are false
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