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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 7, Problem 7.2.1b

1. Express the following logarithms in terms of ln 2 and ln 3.
b. ln(4/9)

Verified step by step guidance
1
Recall the logarithm property that allows you to express the logarithm of a quotient as the difference of logarithms: \(\ln\left(\frac{a}{b}\right) = \ln a - \ln b\).
Apply this property to the given expression: \(\ln\left(\frac{4}{9}\right) = \ln 4 - \ln 9\).
Express 4 and 9 in terms of their prime factors: \(4 = 2^2\) and \(9 = 3^2\).
Use the logarithm power rule, which states \(\ln(a^b) = b \ln a\), to rewrite \(\ln 4\) and \(\ln 9\) as \(2 \ln 2\) and \(2 \ln 3\) respectively.
Combine these results to express the original logarithm entirely in terms of \(\ln 2\) and \(\ln 3\): \(\ln\left(\frac{4}{9}\right) = 2 \ln 2 - 2 \ln 3\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Properties of Logarithms

Logarithms have key properties such as the product, quotient, and power rules. The quotient rule states that ln(a/b) = ln(a) - ln(b), allowing the expression of logarithms of fractions as differences of logarithms.
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Change of Base Property

Natural Logarithm (ln)

The natural logarithm, denoted ln, is the logarithm with base e. It is commonly used in calculus and can be manipulated using its properties to simplify expressions involving constants like 2 and 3.
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Derivative of the Natural Logarithmic Function

Expressing Numbers as Powers or Products

To rewrite logarithms in terms of ln 2 and ln 3, numbers like 4 and 9 should be expressed as powers or products of 2 and 3, e.g., 4 = 2^2 and 9 = 3^2, enabling the use of the power rule for logarithms.
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The Product Rule Example 1