Let (an) and (bn)1 be two sequences. Assume that the sequence (Σ1 ak)=1 is bounded, and that (bn) is decreasing n= with limit 0. Show that Σanbn n=1 n N k=1 is convergent. [HINT: Let An = Σ²_1 ªk. Then show that _1 anbn: ANON+1 An (bn — bn+1), and that Σn An (bn — bn+1) is absolutely convergent. For the last, you may need the Direct Comparison Test n=1 =

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question
Let (an) and (bn)1 be two sequences. Assume that
the sequence (1 ak)=1 is bounded, and that (bn)_₁ is decreasing
n=
with limit 0. Show that
Σanbn
n=1
n
N
is convergent. [HINT: Let An = Σ²_1 ªk. Then show that _1 anbn:
=
k=1
N-1
n=1
ANON +1 An (bn — bn+1), and that Σn An(bn − bn+1) is absolutely
convergent. For the last, you may need the Direct Comparison Test
Transcribed Image Text:Let (an) and (bn)1 be two sequences. Assume that the sequence (1 ak)=1 is bounded, and that (bn)_₁ is decreasing n= with limit 0. Show that Σanbn n=1 n N is convergent. [HINT: Let An = Σ²_1 ªk. Then show that _1 anbn: = k=1 N-1 n=1 ANON +1 An (bn — bn+1), and that Σn An(bn − bn+1) is absolutely convergent. For the last, you may need the Direct Comparison Test
Expert Solution
steps

Step by step

Solved in 7 steps with 7 images

Blurred answer
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,