(5x)" . Given the power series Σ(-1)", , find and justify its interval of 4n In(n)' n=2 onvergence and the behavior of the series at the end points of the interval.

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
icon
Related questions
Question
### Problem 8: Interval of Convergence for a Power Series

#### Given Problem Statement:
Given the power series 

\[ \sum_{n=2}^{\infty} \frac{(-1)^n (5x)^n}{4^n \ln(n)} \],

find and justify its interval of convergence and the behavior of the series at the end points of the interval.

#### Steps to Solve the Problem:

1. **Ratio Test for Convergence:**
   The ratio test will be used to find the interval of convergence. Given a general term \( a_n = \frac{(-1)^n (5x)^n}{4^n \ln(n)} \), we apply the ratio test:

   \[
   \left| \frac{a_{n+1}}{a_n} \right| = \left| \frac{ \frac{(-1)^{n+1} (5x)^{n+1}}{4^{n+1} \ln(n+1)} }{ \frac{(-1)^n (5x)^n}{4^n \ln(n)} } \right| = \left| \frac{(5x)^{n+1}}{4^{n+1} \ln(n+1)} \cdot \frac{4^n \ln(n)}{(5x)^n} \right|
   \]

   Simplifying this, we get:

   \[
   \left| \frac{(5x)(5x)^n}{4 \cdot 4^n \ln(n+1)} \cdot \frac{4^n \ln(n)}{(5x)^n} \right| = \left| \frac{5x}{4} \cdot \frac{\ln(n)}{\ln(n+1)} \right|
   \]

   As \( n \to \infty \), \(\frac{\ln(n)}{\ln(n+1)} \to 1\). Hence, 

   \[
   \lim_{n \to \infty} \left| \frac{a_{n+1}}{a_n} \right| = \left| \frac{5x}{4} \right|
   \]

   For convergence, the limit should be less than 1:

   \[
   \left| \frac{5x}{4} \
Transcribed Image Text:### Problem 8: Interval of Convergence for a Power Series #### Given Problem Statement: Given the power series \[ \sum_{n=2}^{\infty} \frac{(-1)^n (5x)^n}{4^n \ln(n)} \], find and justify its interval of convergence and the behavior of the series at the end points of the interval. #### Steps to Solve the Problem: 1. **Ratio Test for Convergence:** The ratio test will be used to find the interval of convergence. Given a general term \( a_n = \frac{(-1)^n (5x)^n}{4^n \ln(n)} \), we apply the ratio test: \[ \left| \frac{a_{n+1}}{a_n} \right| = \left| \frac{ \frac{(-1)^{n+1} (5x)^{n+1}}{4^{n+1} \ln(n+1)} }{ \frac{(-1)^n (5x)^n}{4^n \ln(n)} } \right| = \left| \frac{(5x)^{n+1}}{4^{n+1} \ln(n+1)} \cdot \frac{4^n \ln(n)}{(5x)^n} \right| \] Simplifying this, we get: \[ \left| \frac{(5x)(5x)^n}{4 \cdot 4^n \ln(n+1)} \cdot \frac{4^n \ln(n)}{(5x)^n} \right| = \left| \frac{5x}{4} \cdot \frac{\ln(n)}{\ln(n+1)} \right| \] As \( n \to \infty \), \(\frac{\ln(n)}{\ln(n+1)} \to 1\). Hence, \[ \lim_{n \to \infty} \left| \frac{a_{n+1}}{a_n} \right| = \left| \frac{5x}{4} \right| \] For convergence, the limit should be less than 1: \[ \left| \frac{5x}{4} \
Expert Solution
steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Similar questions
Recommended textbooks for you
Calculus: Early Transcendentals
Calculus: Early Transcendentals
Calculus
ISBN:
9781285741550
Author:
James Stewart
Publisher:
Cengage Learning
Thomas' Calculus (14th Edition)
Thomas' Calculus (14th Edition)
Calculus
ISBN:
9780134438986
Author:
Joel R. Hass, Christopher E. Heil, Maurice D. Weir
Publisher:
PEARSON
Calculus: Early Transcendentals (3rd Edition)
Calculus: Early Transcendentals (3rd Edition)
Calculus
ISBN:
9780134763644
Author:
William L. Briggs, Lyle Cochran, Bernard Gillett, Eric Schulz
Publisher:
PEARSON
Calculus: Early Transcendentals
Calculus: Early Transcendentals
Calculus
ISBN:
9781319050740
Author:
Jon Rogawski, Colin Adams, Robert Franzosa
Publisher:
W. H. Freeman
Precalculus
Precalculus
Calculus
ISBN:
9780135189405
Author:
Michael Sullivan
Publisher:
PEARSON
Calculus: Early Transcendental Functions
Calculus: Early Transcendental Functions
Calculus
ISBN:
9781337552516
Author:
Ron Larson, Bruce H. Edwards
Publisher:
Cengage Learning