Use properties of logarithms to condense each logarithmic expression. Write the expression as a single logarithm whose coefficient is 1. Where possible, evaluate logarithmic expressions without using a calculator. ln x + ln 7
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Properties of Logarithms
Problem 47
Textbook Question
Find each value. If applicable, give an approximation to four decimal places. ln 1/e2
Verified step by step guidance1
Recall the properties of logarithms, especially the natural logarithm (ln). The natural logarithm of a quotient can be written as the difference of logarithms: \(\ln \left( \frac{a}{b} \right) = \ln a - \ln b\).
Rewrite the expression \(\ln \left( \frac{1}{e^2} \right)\) using the logarithm property: \(\ln 1 - \ln e^2\).
Evaluate \(\ln 1\). Since the natural logarithm of 1 is always 0, we have \(\ln 1 = 0\).
Evaluate \(\ln e^2\). Using the property \(\ln e^x = x\), this simplifies to \$2$.
Combine the results: \$0 - 2 = -2$. This is the exact value of the expression.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Natural Logarithm (ln)
The natural logarithm, denoted as ln, is the logarithm to the base e, where e ≈ 2.718. It answers the question: to what power must e be raised to get a given number? For example, ln(e) = 1 because e^1 = e.
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Properties of Exponents
Exponents represent repeated multiplication. Key properties include e^a * e^b = e^(a+b) and (e^a)^b = e^(ab). Understanding these helps simplify expressions inside logarithms, such as rewriting 1/e^2 as e^(-2).
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Rational Exponents
Logarithm of a Power
The logarithm of a power follows the rule ln(a^b) = b * ln(a). This allows simplification of logarithmic expressions by bringing the exponent down as a multiplier, making calculations easier, especially when the base matches the logarithm's base.
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