Formula for the Sum of a Finite Series

Oct 13, 2025 by talynt.org 109 views

Introduction

In mathematics, the concept of a series and its sum is a fundamental topic in algebra and calculus. A series is the sum of the terms of a sequence, and it can be finite or infinite. In this article, we will evaluate a given series and find its first term. The series is represented as $\sum_{n=1}^5 6(2)^{n-1}$ , and we need to find the value of the first term, denoted by $a$ .

Understanding the Series

The given series is a finite series, which means it has a finite number of terms. It is represented as $\sum_{n=1}^5 6(2)^{n-1}$ . This means that the series has 5 terms, and each term is obtained by multiplying 6 by $2^{n-1}$ , where $n$ ranges from 1 to 5.

Formula for the Sum of a Finite Series

The sum of a finite series can be calculated using the formula:

S = \frac{[a](1-r^n)}{1-r}

where $S$ is the sum of the series, $a$ is the first term, $r$ is the common ratio, and $n$ is the number of terms.

Evaluating the Series

To evaluate the series, we need to find the value of the first term, denoted by $a$ . We can do this by substituting the values of $n$ and $r$ into the formula.

In this case, the common ratio $r$ is 2, and the number of terms $n$ is 5. The first term $a$ is obtained by multiplying 6 by $2^{1-1}$ , which is equal to 6.

Calculating the Sum

Now that we have found the value of the first term, we can calculate the sum of the series using the formula:

S = \frac{[a](1-r^n)}{1-r}

Substituting the values of $a$ , $r$ , and $n$ , we get:

S = \frac{6(1-2^5)}{1-2}

Simplifying the expression, we get:

S = \frac{6(1-32)}{-1}

S = \frac{6(-31)}{-1}

S = 186

Conclusion

In this article, we evaluated a given series and found its first term. The series was represented as $\sum_{n=1}^5 6(2)^{n-1}$ , and we used the formula for the sum of a finite series to calculate its sum. We found that the first term $a$ is equal to 6, and the sum of the series $S$ is equal to 186.

Discussion

The concept of a series and its sum is a fundamental topic in mathematics, and it has numerous applications in various fields, including physics, engineering, and economics. The formula for the sum of a finite series is a powerful tool that can be used to calculate the sum of a series with a finite number of terms.

Example

Suppose we have a series represented as $\sum_{n=1}^3 4(3)^{n-1}$ . We can use the formula for the sum of a finite series to calculate its sum.

First, we need to find the value of the first term $a$ . We can do this by substituting the values of $n$ and $r$ into the formula.

In this case, the common ratio $r$ is 3, and the number of terms $n$ is 3. The first term $a$ is obtained by multiplying 4 by $3^{1-1}$ , which is equal to 4.

Next, we can calculate the sum of the series using the formula:

S = \frac{[a](1-r^n)}{1-r}

Substituting the values of $a$ , $r$ , and $n$ , we get:

S = \frac{4(1-3^3)}{1-3}

Simplifying the expression, we get:

S = \frac{4(1-27)}{-2}

S = \frac{4(-26)}{-2}

S = 52

Applications

The concept of a series and its sum has numerous applications in various fields, including physics, engineering, and economics. For example, in physics, the sum of a series can be used to calculate the total energy of a system. In engineering, the sum of a series can be used to calculate the total stress on a structure. In economics, the sum of a series can be used to calculate the total value of a portfolio.

Conclusion

Introduction

In our previous article, we evaluated a given series and found its first term. The series was represented as $\sum_{n=1}^5 6(2)^{n-1}$ , and we used the formula for the sum of a finite series to calculate its sum. In this article, we will answer some frequently asked questions about evaluating series and finding first terms.

Q: What is a series in mathematics?

A: A series is the sum of the terms of a sequence. It can be finite or infinite, and it is represented by a mathematical expression, such as $\sum_{n=1}^5 6(2)^{n-1}$ .

Q: How do I evaluate a series?

A: To evaluate a series, you need to find the value of the first term, denoted by $a$ , and the common ratio, denoted by $r$ . You can then use the formula for the sum of a finite series to calculate the sum of the series.

Q: What is the formula for the sum of a finite series?

A: The formula for the sum of a finite series is:

S = \frac{[a](1-r^n)}{1-r}

where $S$ is the sum of the series, $a$ is the first term, $r$ is the common ratio, and $n$ is the number of terms.

Q: How do I find the first term of a series?

A: To find the first term of a series, you need to substitute the values of $n$ and $r$ into the formula for the first term. For example, if the series is represented as $\sum_{n=1}^5 6(2)^{n-1}$ , the first term is obtained by multiplying 6 by $2^{1-1}$ , which is equal to 6.

Q: What is the common ratio of a series?

A: The common ratio of a series is the ratio of each term to the previous term. For example, if the series is represented as $\sum_{n=1}^5 6(2)^{n-1}$ , the common ratio is 2.

Q: How do I calculate the sum of a series?

A: To calculate the sum of a series, you need to substitute the values of $a$ , $r$ , and $n$ into the formula for the sum of a finite series. For example, if the series is represented as $\sum_{n=1}^5 6(2)^{n-1}$ , the sum is calculated as:

S = \frac{6(1-2^5)}{1-2}

Simplifying the expression, we get:

S = \frac{6(-31)}{-1}

S = 186

Q: What are some common applications of series in mathematics?

A: Series have numerous applications in various fields, including physics, engineering, and economics. For example, in physics, the sum of a series can be used to calculate the total energy of a system. In engineering, the sum of a series can be used to calculate the total stress on a structure. In economics, the sum of a series can be used to calculate the total value of a portfolio.

Q: What are some common mistakes to avoid when evaluating series?

A: Some common mistakes to avoid when evaluating series include:

Not substituting the correct values of $a$ , $r$ , and $n$ into the formula for the sum of a finite series.
Not simplifying the expression correctly.
Not checking for errors in the calculation.

Conclusion

In this article, we answered some frequently asked questions about evaluating series and finding first terms. We hope that this article has provided you with a better understanding of series and how to evaluate them. If you have any further questions, please don't hesitate to ask.

Example Problems

Evaluate the series $\sum_{n=1}^4 3(4)^{n-1}$ .
Find the first term of the series $\sum_{n=1}^6 2(3)^{n-1}$ .
Calculate the sum of the series $\sum_{n=1}^3 5(2)^{n-1}$ .
What is the common ratio of the series $\sum_{n=1}^5 6(2)^{n-1}$ ?
How do you calculate the sum of a series?

Solutions

The sum of the series is calculated as:

S = \frac{3(1-4^4)}{1-4}

Simplifying the expression, we get:

S = \frac{3(-255)}{-3}

S = 255

The first term of the series is obtained by multiplying 2 by $3^{1-1}$ , which is equal to 2.
The sum of the series is calculated as:

S = \frac{5(1-2^3)}{1-2}

Simplifying the expression, we get:

S = \frac{5(-7)}{-1}

S = 35

The common ratio of the series is 2.
To calculate the sum of a series, you need to substitute the values of $a$ , $r$ , and $n$ into the formula for the sum of a finite series.