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91Ó°ÊÓ

Find the sum. $$\sum_{i=4}^{12} 10$$

Short Answer

Expert verified
The sum is 90.

Step by step solution

01

Understand the Series Summation

The notation \(\sum_{i=4}^{12} 10\) represents a series summation where the upper limit is 12, the lower limit is 4, and the constant term to add is 10 for each integer within this range. We need to add the number 10 for each value of \(i\), starting from 4 up to 12.
02

Count the Number of Terms

To find how many terms are in the series, we subtract the starting index from the ending index and add 1. This is calculated as follows: \(12 - 4 + 1 = 9\). Thus, there are 9 terms in this summation.
03

Multiply the Constant by the Number of Terms

Since each term in the series is 10 and there are 9 terms, the sum of the series is simply the constant term multiplied by the number of terms: \(10 \times 9 = 90\).

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Key Concepts

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

Understanding Series in Mathematics
In mathematics, a series is essentially a summation of a sequence of terms. These terms are often arranged in an arithmetic or geometric order. Typically, when you hear the term 'series', it might refer to the finite sum of elements, as it is bounded by an upper and lower limit.
When dealing with series, it's important to familiarize yourself with its notation. In series notation, the letter Sigma (\( \Sigma \)) is used to represent the sum. For instance, \( \sum_{i=4}^{12} 10 \) means you will be summing a sequence from index 4 to 12. Every integer value between 4 and 12 will be a point at which the constant term is summed.
Thus, understanding series involves recognizing how its notation expresses the sum of a sequence of numbers based on their arrangement and limits indicated above and below the Sigma.
The Role of a Constant Term in Series
A constant term in the context of a series is a number that remains unchanged across the terms being summed. In many exercises involving series, you will encounter scenarios where each term in the series is equivalent due to this constant value.
The constant term has a simplifying effect on the calculations necessary to find the sum. Since a constant term, like 10 in our exercise, does not change regardless of the value of the index, we simply multiply this constant by the number of terms within the defined range.
  • This makes calculations straightforward as each addition follows identical rules.
  • In our example, the constant term 10 is added 9 times because there are 9 integer values from 4 to 12.

In summary, a constant term greatly simplifies series calculations by eliminating variability among the terms being added.
Index Range and Its Importance
The index range in a series is crucial because it defines the boundaries of the summation. It indicates where the series begins and ends, using the lower and upper limits respectively. For instance, in \( \sum_{i=4}^{12} 10 \), the lower limit is 4 and the upper limit is 12.
This range of indices tells us how many terms we will be adding. In order to calculate the number of terms, you simply subtract the lower limit from the upper limit and add 1. For our series, the calculation is \( 12 - 4 + 1 = 9 \), indicating there are 9 terms in total.
  • The index range ensures we are counting and summing the correct number of elements.
  • It's crucial in defining the complete scope of our summation process.
By understanding the index range, you ensure precision in how you approach and solve series summations.

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