Chapter 10: Problem 5
Write out each finite series. $$ \sum_{n=1}^{6} \frac{1-(-1)^{n}}{2} $$
Short Answer
Expert verified
The sum of the series is 3.
Step by step solution
01
Understand the Series
The series given is \( \sum_{n=1}^{6} \frac{1-(-1)^{n}}{2} \). We need to compute the value for each term from \( n=1 \) to \( n=6 \).
02
Calculate Individual Terms
For each \( n \):- When \( n = 1 \), \( (-1)^1 = -1 \), so \( \frac{1 - (-1)^1}{2} = \frac{1 + 1}{2} = 1 \).- When \( n = 2 \), \( (-1)^2 = 1 \), so \( \frac{1 - (-1)^2}{2} = \frac{1 - 1}{2} = 0 \).- When \( n = 3 \), \( (-1)^3 = -1 \), so \( \frac{1 - (-1)^3}{2} = \frac{1 + 1}{2} = 1 \).- When \( n = 4 \), \( (-1)^4 = 1 \), so \( \frac{1 - (-1)^4}{2} = \frac{1 - 1}{2} = 0 \).- When \( n = 5 \), \( (-1)^5 = -1 \), so \( \frac{1 - (-1)^5}{2} = \frac{1 + 1}{2} = 1 \).- When \( n = 6 \), \( (-1)^6 = 1 \), so \( \frac{1 - (-1)^6}{2} = \frac{1 - 1}{2} = 0 \).
03
Write the Series
The series can now be written as: \( 1 + 0 + 1 + 0 + 1 + 0 \).
04
Calculate the Sum
Add the terms: \( 1 + 0 + 1 + 0 + 1 + 0 = 3 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Arithmetic Sequences
An arithmetic sequence is a list of numbers where each term differs from the next by a constant value. This difference is known as the common difference. For example, in the sequence 2, 4, 6, 8, the common difference is 2.
- To find any term in an arithmetic sequence, you use the formula: \( a_n = a_1 + (n-1) \cdot d \), where \( a_1 \) is the first term, \( d \) is the common difference, and \( n \) is the term number.
- Arithmetic sequences are useful when you need to model situations where something increases or decreases by the same amount every time, like savings plans or sequences in geometry.
- In the context of finite series, arithmetic sequences can be summed up using the formula for the sum of an arithmetic series: \( S_n = \frac{n}{2} \cdot (a_1 + a_n) \), where \( S_n \) is the sum of the first \( n \) terms.
Summation Notation
Summation notation is a way to denote the sum of a sequence of numbers. It is represented by the symbol "Sigma" \( \Sigma \). This notation helps simplify expressions where you'd otherwise have to write out long additions.
- The expression \( \sum_{n=1}^{6} \frac{1-(-1)^{n}}{2} \) is an example of summation notation. It tells you to find the sum of terms generated by the expression \( \frac{1-(-1)^{n}}{2} \) as \( n \) goes from 1 to 6.
- Summation is a key concept in mathematics because it provides a concise way to represent the sum of a potentially large number of terms. For finite series, it guarantees that the process of summing up the terms will eventually end, unlike infinite series.
- To break down summations further, it often helps to calculate the value of the expression for each individual \( n \) and then sum up the results, just as we've done in this exercise.
Calculus Basics
Calculus is a branch of mathematics focused on studying rates of change (differential calculus) and accumulation of quantities (integral calculus). It stands as a fundamental tool in mathematics with applications across science and engineering.
- Although our exercise deals with a finite series, calculus is essential in understanding infinite series and the concept of convergence, where series approach a limit.
- Differentiation, one of the main operations in calculus, helps find the rate at which a quantity changes relative to another. Integration, its counterpart, computes the total accumulation of a quantity over an interval.
- In more advanced topics, calculus makes use of summation notation to express integrals and derivatives, depicting areas under curves and slopes of functions respectively.