Math Problem Statement

Consider the sum of the first n terms of the series S_n = Σ (1/k^p) for k=1 to n, with p > 1. (a) Show that S_n is bounded for p > 1. (b) Prove or disprove that S_n converges as n → ∞ for p = 1, p > 1, and p < 1.

Solution

The image contains a problem related to the limit of a series. Here is a transcription of the problem:


Exercise:
Consider the sum of the first nn terms of the series Sn=k=1n1kpS_n = \sum_{k=1}^{n} \frac{1}{k^p} with p>1p > 1.

(a) Show that SnS_n is bounded for p>1p > 1.

(b) Prove or disprove that SnS_n converges as nn \to \infty for p=1p = 1, p>1p > 1, and p<1p < 1.


This problem involves series convergence and bounding. Let's break it down.

(a) Showing that SnS_n is bounded for p>1p > 1:

For p>1p > 1, we need to show that the sum of the series is bounded as nn increases. This involves finding an upper limit that the sum does not exceed.

Hint:

One approach is to compare SnS_n with an integral. For p>1p > 1, k=11kp\sum_{k=1}^{\infty} \frac{1}{k^p} is a convergent p-series, which implies that the partial sums SnS_n are bounded.

(b) Convergence analysis for different values of pp:

  • For p>1p > 1: The series SnS_n converges as nn \to \infty.
  • For p=1p = 1: The series SnS_n becomes the harmonic series, which diverges.
  • For p<1p < 1: The series diverges more rapidly because the terms do not decrease fast enough.

If you need further explanation or help with solving the problem step-by-step, feel free to ask!


Would you like detailed steps for proving part (a) or analyzing part (b)?

Related Questions:

  1. How can we use the integral test to determine if a series converges?
  2. What is the difference between a convergent and divergent series?
  3. How does the value of pp affect the convergence of the p-series?
  4. Can you give an example of a bounded but non-convergent sequence?
  5. What is the significance of the harmonic series in mathematical analysis?

Tip:

When dealing with series, always consider using convergence tests like the integral test, comparison test, and ratio test to analyze the behavior as nn approaches infinity.

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Math Problem Analysis

Mathematical Concepts

Series Convergence
p-Series
Boundedness
Divergence

Formulas

S_n = Σ (1/k^p) for k=1 to n

Theorems

p-Series Test
Integral Test

Suitable Grade Level

University-Level