Chapter 14: Problem 16
Evaluate. See Example 1 $$ \sum_{i=1}^{4} 3^{i-1} $$
Short Answer
Expert verified
The sum is 40.
Step by step solution
01
Understanding the Problem
We need to evaluate the expression \( \sum_{i=1}^{4} 3^{i-1} \). This is a summation notation that tells us to sum up the values of \( 3^{i-1} \) from \( i = 1 \) to \( i = 4 \).
02
Calculating Each Term
Let's calculate each term individually:- For \( i = 1 \): \( 3^{1-1} = 3^0 = 1 \).- For \( i = 2 \): \( 3^{2-1} = 3^1 = 3 \).- For \( i = 3 \): \( 3^{3-1} = 3^2 = 9 \).- For \( i = 4 \): \( 3^{4-1} = 3^3 = 27 \).
03
Summing the Terms
Now, sum the calculated values from each term:\[ 1 + 3 + 9 + 27 \]
04
Calculating the Sum
Sum the numbers:\( 1 + 3 = 4 \)\( 4 + 9 = 13 \)\( 13 + 27 = 40 \)
05
Final Evaluation
The final summed value is \( 40 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Functions
Exponential functions are a type of mathematical function in which a constant base is raised to a variable exponent. In other words, the function is expressed as \(b^x\), where \(b\) is a fixed number known as the base, and \(x\) is the variable exponent. In the given exercise, we have an exponential function \(3^{i-1}\).There are several important properties to remember about exponential functions:
- The base: Needs to be a positive number. In our problem, the base is \(3\).
- The exponent: Directly affects the calculation. Here, the exponent is \(i-1\).
- Exponential growth: As the exponent increases, the value of the function grows rapidly.
Series Evaluation
Series evaluation involves finding the sum of a sequence of numbers or terms. In the context of our exercise, the series we are evaluating is the summation from \(i=1\) to \(i=4\) of \(3^{i-1}\).To evaluate such a series:
- Identify each term of the series. In our case, these were \(3^0\), \(3^1\), \(3^2\), and \(3^3\).
- Calculate each term individually before summing them together. Calculating these, we found the terms as 1, 3, 9, and 27.
- Add up all the individual terms to get the series' total sum: \(1 + 3 + 9 + 27 = 40\).
Algebraic Expressions
An algebraic expression is a mathematical phrase that can contain numbers, variables, and operations such as addition, subtraction, multiplication, and division. In our exercise, the expression \(3^{i-1}\) is an algebraic expression consisting of a constant base and a variable exponent achieved through the operation of exponentiation.When working with algebraic expressions:
- Identify the components: Recognize constants (like the number 3 in \(3^{i-1}\)), variables (like \(i\)), and operations.
- Manipulate the expressions systematically, if necessary, to perform calculations in a structured way. This includes careful handling of exponentiation and understanding its impact on the expression's value.
- Simplify and solve expressions step-by-step to lessen errors and aid in understanding complex problems.