The product of absconverg series and bounded seq is absolutely convergent

Can you provide a summary of the conversation?In summary, the problem states that if \sum_{1}^{\infty} a_n is absolutely convergent and {b_n} is bounded, we need to prove that \sum_{1}^{\infty} a_n * b_n is also absolutely convergent. The key equations used are the criteria for absolute convergence and the Cauchy sequence of partial sums. The solution involves showing that the sequence of partial sums for \sum_{1}^{\infty} a_n * b_n is Cauchy using the boundedness of {b_n}.
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Homework Statement


Assume [tex]\sum_{1}^{\infty} a_n[/tex] is absolutely convergent and {bn} is bounded. Prove [tex]\sum_{1}^{\infty} a_n * b_n[/tex] is absolutely convergent


Homework Equations


A series is absolutely convergent iff the sum of | an | is convergent

A series is convergent if for every e there is an N and P such that for all n >= N, for all p >0,
| S_{n+p} - S{n-1} | < e. S_k is the kth partial sum, and this basically says that the sequence of partial sum must be cauchy.


The Attempt at a Solution



because the series of an is abosultely convergent | |a_{n+p}| - |a_{n-1}| | < e
and bn is bounded means | b_n| < M

[tex] \left| \left| a_{n+p} b_{n+p} \right| - \left| a_{n-1}b_{n-1} \right| \right| \leq \left| a_{n+p} b_{n+p} \right| + \left| a_{n-1} b_{n-1} \right| \leq M \left| a_{n+p} \right| + M \left| a_{n-1} \right| < \frac{Me}{2M} + \frac{Me}{2M} = e [/tex]

done
 
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I'm confused...do you have a question?
 

FAQ: The product of absconverg series and bounded seq is absolutely convergent

What is the product of an absolutely convergent series and a bounded sequence?

The product of an absolutely convergent series and a bounded sequence is also absolutely convergent. This means that the sum of the product of the series and the sequence will converge to a finite value.

How do you determine if a series is absolutely convergent?

A series is absolutely convergent if the absolute value of each term in the series converges to a finite value. This means that even if the signs of the terms change, the series will still converge.

Can a series be absolutely convergent but not convergent?

No, a series cannot be absolutely convergent but not convergent. If a series is absolutely convergent, it means that the series itself is also convergent.

What is the importance of knowing the product of an absolutely convergent series and a bounded sequence?

Knowing the product of an absolutely convergent series and a bounded sequence can help in solving various mathematical problems, especially in the field of analysis. It can also aid in understanding the behavior and properties of series and sequences.

Are there any exceptions to the rule that the product of an absolutely convergent series and a bounded sequence is absolutely convergent?

Yes, there are some exceptions to this rule. For example, if the sequence is not bounded or the series is not absolutely convergent, then the product may not be absolutely convergent. It is important to consider the individual properties of each series and sequence when determining the convergence of their product.

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