Math Problem Statement
Solution
The given series is:
We are tasked with showing that this series is absolutely convergent if .
Step-by-step solution:
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Absolute Convergence: For absolute convergence, we need to check the convergence of the series of the absolute values of the terms:
This is now a non-alternating positive series.
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Convergence Test: To determine the convergence of this series, we will use the integral test. The integral test states that if the function is positive, continuous, and decreasing for , then the convergence of the integral:
is equivalent to the convergence of the series .
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Integral Calculation: Let's calculate the improper integral:
To solve this, we use the substitution , which gives . The limits of integration change accordingly:
- When , ,
- When , .
Thus, the integral becomes:
The integral converges if and only if , because for , it would diverge as a logarithmic integral, and for , the exponent is too small for convergence.
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Conclusion: The series converges if based on the integral test. Hence, the original series is absolutely convergent for .
Would you like further details on any part of the explanation?
Here are some related questions:
- How does the integral test work for series convergence?
- Why is the substitution helpful in the integral calculation?
- What is the difference between absolute convergence and conditional convergence?
- What happens to the series if ?
- How would you handle this series if it didn't alternate (i.e., without the factor)?
Tip: The integral test is a powerful tool for series with logarithmic or power terms. Always check the conditions where the function behaves continuously and decreases to apply it.
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Math Problem Analysis
Mathematical Concepts
Series Convergence
Logarithmic Series
Integral Test
Formulas
Absolute convergence: ∑ |(-1)^n / [n(log n)^p]| = ∑ 1 / [n(log n)^p]
Integral for convergence: ∫ 1 / [x(log x)^p] dx
Theorems
Integral Test
Suitable Grade Level
Undergraduate Mathematics (Calculus II or III)
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