Limit of Infinite Series | Solving y = (2n+3n)/4n | Homework Statement

In summary, the conversation discusses finding the limit of the sum of a series, which is two separate geometric series. The first problem is relatively easy, but the second one is more challenging and involves finding the sum of the areas of all the geometric figures. The solution to the second problem is not immediately clear and may require further research.
  • #1
steve2212
11
0

Homework Statement


Find the limit of the sum of:

y = (2n + 3n) / 4n

The Attempt at a Solution



as n-> infinity, y approaches 0. I don't know where to proceed from here.
 
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  • #2
It's 2^n/4^n+3^n/4^n=(2/4)^n+(3/4)^n. It's two separate geometric series. Can you deal with those?
 
  • #3
Dick said:
It's 2^n/4^n+3^n/4^n=(2/4)^n+(3/4)^n. It's two separate geometric series. Can you deal with those?

Ya I got that but I don't know how to find the sum of an infinite geometric series
 
  • #4
steve2212 said:
Ya I got that but I don't know how to find the sum of an infinite geometric series

That's regrettable. Then you should probably try to look it up in your text or online. It's pretty basic.
 
  • #5
Oh sorry I'm stupid, I remembered how haha.

Since you're here I also have another hard one.

A circle is inscribed in a triangle, a square is inscribed in that circle, a circle is inscribed is that square, a pentagon is inscribed in that circle, the trend continues with the degree going up.

How do I proceed to solve this quesiton? I need to find t he sum of the limit
 
  • #6
steve2212 said:
Oh sorry I'm stupid, I remembered how haha.

Since you're here I also have another hard one.

A circle is inscribed in a triangle, a square is inscribed in that circle, a circle is inscribed is that square, a pentagon is inscribed in that circle, the trend continues with the degree going up.

How do I proceed to solve this quesiton? I need to find t he sum of the limit

The first one wasn't hard. That one probably is. What are to trying to find the sum or the limit of? The areas, or the perimeters or the radii, or what? Not that I know the answer. But your question isn't even clear.
 
  • #7
The limit of the sum of the area. Sorry forgot that detail.
 
  • #8
steve2212 said:
The limit of the sum of the area. Sorry forgot that detail.

The sum of the areas of ALL of the geometric figures? I think it's pretty likely it diverges. Mostly gut feeling. Is this for a class, or is this your own creation? It's way out of scale with the difficulty of your first problem.
 
  • #9
It was a bonus question on our test yesterday. Yup we need the limit of the sum of all of the areas. I know that the areas of the figures approach to 0 that's easy.
 
  • #10
How do you know the areas approach zero? Sure, they decrease. But that doesn't convince me that they approach zero. Do you know this has a simple solution? Because I'm sure not seeing it.
 
  • #11
Dick said:
How do you know the areas approach zero? Sure, they decrease. But that doesn't convince me that they approach zero. Do you know this has a simple solution? Because I'm sure not seeing it.

Area can't be negative, and area decreases, it has to approach 0. Right?
 
  • #12
steve2212 said:
Area can't be negative, and area decreases, it has to approach 0. Right?

Nope. 1+1/n is a positive decreasing sequence but it doesn't approach 0. It approaches 1.
 
  • #13
Sorry where do you get 1+ 1/n?
 
  • #14
steve2212 said:
Sorry where do you get 1+ 1/n?

It's just an example of a sequence that decreases but doesn't approach zero.
 

Related to Limit of Infinite Series | Solving y = (2n+3n)/4n | Homework Statement

What is the sum of an infinite series?

The sum of an infinite series is the total value obtained by adding up an infinite number of terms. This is often represented by the symbol ∑, which stands for "sum". Infinite series are important in mathematics and physics, as they can be used to approximate values and solve equations.

How is the sum of an infinite series calculated?

The sum of an infinite series is calculated using a specific formula or method, depending on the type of series. Some common methods include the geometric series formula, the telescoping series method, and the ratio test. It is important to note that not all infinite series have a finite sum.

What is a convergent series?

A convergent series is an infinite series that has a finite sum. This means that the total value obtained by adding up all the terms in the series is a real number. Convergent series are important in calculus and are used to evaluate integrals and solve differential equations.

What is a divergent series?

A divergent series is an infinite series that does not have a finite sum. This means that no matter how many terms are added, the total value will continue to increase or decrease without ever reaching a fixed value. Divergent series can be used in certain mathematical proofs and also have applications in physics.

How are infinite series used in real life?

Infinite series have many practical applications in real life, particularly in the fields of mathematics, physics, and engineering. They are used to approximate values and solve equations, and can also be used to model real-world phenomena such as population growth, financial investments, and electrical circuits. Infinite series also play a role in computer science and data analysis.

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