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In Exercises 69-80, determine the convergence or divergence of the series. $$\sum_{n=1}^{\infty}\left(\frac{1}{n^{2}}-\frac{1}{n^{3}}\right)$$

Short Answer

Expert verified
The given series \(\sum_{n=1}^{\infty}\left(\frac{1}{n^{2}}-\frac{1}{n^{3}}\right)\) is convergent.

Step by step solution

01

Separate the series

First, separate this series into two distinct series. We get \(\sum_{n=1}^{\infty}\frac{1}{n^{2}}\) and \(\sum_{n=1}^{\infty}\frac{1}{n^{3}}\).
02

Determine the convergence of each series

Check if each of these series converge or diverge. The series \(\sum_{n=1}^{\infty}\frac{1}{n^{2}}\) is known as a p-series, where p equals 2, greater than 1, thus it converges. Moreover, the series \(\sum_{n=1}^{\infty}\frac{1}{n^{3}}\) is also a p-series but with p=3, thus also converges.
03

Combine the results

Combine the results of both series. As both the series are convergent, their difference (original series) is also convergent.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding p-series
A p-series is a special type of infinite series that takes the form \(\sum_{n=1}^{\infty} \frac{1}{n^p}\), where \(p\) is a constant. These series are extremely important when studying convergence because their behavior is well understood. The key thing to remember is that a p-series will converge if and only if \(p > 1\).
In our original problem, we come across two p-series: \(\sum_{n=1}^{\infty} \frac{1}{n^2}\) and \(\sum_{n=1}^{\infty} \frac{1}{n^3}\).
Since both have \(p\) values greater than 1 (2 and 3, respectively), both series converge. This understanding is a cornerstone in checking the behavior of other similar series easily.
A Look at Convergence Tests
Convergence tests are mathematical methods used to determine whether an infinite series converges or diverges. These tests help us understand the behavior of a series without having to fully evaluate it.
There are several commonly used convergence tests, such as the Ratio Test, Root Test, and Comparison Test. However, in the context of p-series, the p-series test is a simple and efficient approach.
For the problem at hand, using the p-series test, we identified that both series \(\sum_{n=1}^{\infty} \frac{1}{n^2}\) and \(\sum_{n=1}^{\infty} \frac{1}{n^3}\) converge, because the exponent \(p\) is greater than 1 for both. This test saves time and helps in quickly determining the convergence of p-series functions by simply checking the value of \(p\).
These insights into convergence tests give us a fast-track way to solve a myriad of problems involving infinite series.
Infinite Series Explained
An infinite series is the sum of an infinite sequence of numbers. It often takes the form \(\sum_{n=1}^{\infty} a_n\), where \(a_n\) represents the terms of the series. A key question for any infinite series is whether it converges, meaning does it approach a particular value as more terms are added.
In the context of the given problem, it's vital to grasp that different types of infinite series behave differently. For instance, a harmonic series, generally given as \(\sum_{n=1}^{\infty} \frac{1}{n}\), diverges, as it doesn't approach any limit. This contrasts with p-series, where we know they converge when \(p > 1\).
Understanding infinite series is crucial since they are widely used in calculus, physics, and engineering to solve various real-world problems. They allow for the approximation of functions, the expansion into simpler forms, and the computation of values that are otherwise challenging to determine.

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Most popular questions from this chapter

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