Find c likes the series is convergent

In summary, the conversation discusses the convergence of the integral \int_0^{\infty}\left(\frac{2x}{x^2+1} - \frac{c}{2x+1}\right)dx and how the value of c affects the convergence. The conversation includes hints and considerations for finding the appropriate value of c for convergence.
  • #1
marrie
2
0
Find c ∈ IR, like ∫∞ ( 2x - c ) dx is convergent
0 X^2 +1 2x+1

I need your help because I was trying to resolve the problem, but I couldn't, is difficult for me.
Please help me!
 
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  • #2
Welcome to PF!

Hi marrie! Welcome to PF! :smile:
marrie said:
Find c ∈ IR, like ∫∞ ( 2x - c ) dx is convergent
0 X^2 +1 2x+1

hmm :rolleyes: … you mean [tex]\int_0^{\infty}\left(\frac{2x}{x^2+1} - \frac{c}{2x+1}\right)dx[/tex] :wink:

Hint:

i] can you integrate each of them separately? does each converge or diverge?

ii] how much faster do you think the bottom needs to increase than the top for the integral to converge? :smile:
 
  • #3
Ok, if I integrate each of them separately, I believe that the series diverge.
And I know that the bottom needs to increase than for the top for the integral converge.
thanks for your hints!
 
  • #4
Hi marrie! :smile:
marrie said:
Ok, if I integrate each of them separately, I believe that the series diverge.
And I know that the bottom needs to increase than for the top for the integral converge.

ah … but how much more than the top? :wink:

anyway, write the whole thing over a common denominator …

then what does c have to be to make the top increase slowly enough? :smile:
 

FAQ: Find c likes the series is convergent

What does it mean for a series to be convergent?

A series is considered convergent if the sum of its terms approaches a finite number as the number of terms increases. In other words, the series has a finite limit, or total value.

How do you determine if a series is convergent?

There are several methods for determining if a series is convergent, including the comparison test, the ratio test, the root test, and the integral test. These tests involve analyzing the behavior of the terms in the series and their relationship to known convergent or divergent series.

Why is it important to know if a series is convergent?

Knowing if a series is convergent is crucial in many areas of mathematics and science. It allows us to make accurate predictions and calculations, such as in finance and engineering. Additionally, it helps us understand the behavior of infinite sums and sequences, which are fundamental concepts in mathematics.

Can a series be both convergent and divergent?

No, a series cannot be both convergent and divergent. A series is either one or the other, based on the behavior of its terms. If the terms approach a finite limit, the series is convergent. If the terms do not approach a finite limit, the series is divergent.

What are some real-world applications of convergent series?

Convergent series have many real-world applications, such as in calculating compound interest in finance, determining the accuracy of numerical methods in computer science, and analyzing the stability of systems in physics and engineering. They are also used in probability and statistics to model and predict various phenomena.

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