Proving series is convergent/divergent

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In summary, the problem is to prove the convergence or divergence of the series ∞Ʃ 1 / [(n)(n+1)(n+2)]^(1/3) where n=1. The suggested methods for approaching this problem are using the limit or direct comparison test, and simplifying the expression by factoring out (n)(n+2)(n+2) and using the properties of exponents. The attempt at using l'Hopital's Rule was deemed unnecessary and too complicated by the presence of the cube root in the expression.
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Homework Statement



The problem is proving that the following series is convergent or divergent:


Ʃ 1 / [(n)(n+1)(n+2)]^(1/3)
n=1

Homework Equations



The limit or direct comparison test

The Attempt at a Solution



lim {1 / [(n)(n+1)(n+2)]^(1/3)} / (1/n)
n->∞

I then attempted to simplify this and use l'Hopital's Rule, but the cube root made it too complicated, and I couldn't come to an answer.
 
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  • #2
abcde149149 said:

Homework Statement



The problem is proving that the following series is convergent or divergent:


Ʃ 1 / [(n)(n+1)(n+2)]^(1/3)
n=1

Homework Equations



The limit or direct comparison test

The Attempt at a Solution



lim {1 / [(n)(n+1)(n+2)]^(1/3)} / (1/n)
n->∞

I then attempted to simplify this and use l'Hopital's Rule, but the cube root made it too complicated, and I couldn't come to an answer.

l'Hopital is serious overkill. (n)(n+2)(n+2)=n^3(1)(1+1/n)(n+2/n). Try simplifying.
 

FAQ: Proving series is convergent/divergent

What is the definition of a convergent series?

A convergent series is a sequence of numbers where the terms get closer and closer to a single finite number as more terms are added. This means that the series has a finite limit or sum.

How do you prove that a series is convergent?

To prove that a series is convergent, you can use several different methods such as the ratio test, the root test, or the comparison test. These tests involve comparing the given series to a known convergent or divergent series and using mathematical properties to determine the convergence or divergence of the given series.

What is the difference between absolute and conditional convergence?

Absolute convergence refers to a series where the individual terms are always positive or always negative. In this case, the series will converge to a finite sum regardless of the order in which the terms are added. Conditional convergence, on the other hand, refers to a series where the individual terms are both positive and negative, and the order in which the terms are added affects the convergence of the series.

What is the divergence test and when should it be used?

The divergence test, also known as the nth term test, is a method used to determine if a series is divergent. It states that if the limit of the nth term of a series is not equal to 0, then the series must be divergent. This test is often used as a first check before using other convergence tests.

What is the importance of proving the convergence or divergence of a series?

Proving the convergence or divergence of a series is important because it allows us to determine whether the series has a finite sum or not. This information is crucial in many mathematical and scientific applications, such as calculating probabilities, approximating values, and solving differential equations.

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