Chapter 6: Problem 17
Write each sum in sigma notation. $$ \ln 2+\ln 3+\ln 4+\ln 5 $$
Short Answer
Expert verified
\( \sum_{n=2}^{5} \ln n \)
Step by step solution
01
Identify the Pattern
Observe that the given terms are natural logarithms of consecutive integers starting from 2 and ending at 5: \( \ln 2, \ln 3, \ln 4, \ln 5 \). This suggests a summation pattern over consecutive numbers.
02
Determine the General Term
The general term that fits each sum is \( \ln n \), where \( n \) is an integer. In this case, \( n \) will take on values that start from 2 and go up to 5.
03
Establish the Range
The sequence begins at the second integer (2) and ends at the fifth integer (5). Hence, the index variable \( n \) will start at 2 and end at 5, indicating the limits of summation.
04
Write in Sigma Notation
Combine the general term and the range to write the sum in sigma notation: \[ \sum_{n=2}^{5} \ln n \]. This represents the sum of \( \ln n \) from \( n = 2 \) to \( n = 5 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Natural Logarithm
The natural logarithm, denoted as \( \ln \), is a logarithm to the base \( e \), where \( e \) is an irrational and transcendental number approximately equal to 2.718. It's a special type of logarithm that is commonly used in mathematics because of its natural properties and simplicity when dealing with exponential growth and decay.
- Properties of Natural Logarithms:
- \( \ln(1) = 0 \): The natural logarithm of 1 is always 0, no matter the base.
- \( \ln(e) = 1 \): Since \( e \) is the base, raising \( e \) to the power of 1 gives \( e \) itself.
- Product rule: \( \ln(a \cdot b) = \ln a + \ln b \).
- Quotient rule: \( \ln(\frac{a}{b}) = \ln a - \ln b \).
- Power rule: \( \ln(a^b) = b \cdot \ln a \).
Summation Pattern in Sigma Notation
Sigma notation is a compact way to represent summation. It uses the Greek letter \( \Sigma \) to list a series of terms, especially useful when dealing with large amounts of similar terms.When observing a summation pattern, we check if the series of terms can be expressed with a simple rule. For example, in our case, we have the summation \( \ln 2 + \ln 3 + \ln 4 + \ln 5 \). This is a pattern of natural logarithms applied to consecutive integers.
- Defining the Pattern:
- The general term here is \( \ln n \), where \( n \) represents the consecutive integers.
- Identifying the starting and ending points: Our sequence starts from 2 and ends at 5.
Role of Consecutive Integers in Sigma Notation
Consecutive integers are a sequence of numbers where each number is one more than the previous one. For instance, the sequence 2, 3, 4, 5 consists of consecutive integers. Identifying such patterns is essential when writing sums in sigma notation.
- Recognizing Consecutiveness:
- Note that each integer differs by exactly 1.
- Helps in determining the range in the sigma notation (lower and upper limits).
- Application to Sigma Notation:
- Consistently structured sequences make sigma notation straightforward and clear.
- In the example \( \ln 2 + \ln 3 + \ln 4 + \ln 5 \), recognizing the integers as consecutive simplifies setting the range from 2 to 5 in \( \sum_{n=2}^{5} \ln n \).