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Ch. 4 - Exponential and Logarithmic Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 65

Solve each logarithmic equation in Exercises 49–92. Be sure to reject any value of xx that is not in the domain of the original logarithmic expressions. Give the exact answer. Then, where necessary, use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution. lnx+3=1\(\ln\]\sqrt{x+3}\)=1

검증된 단계별 안내
1
Rewrite the equation \( \ln \sqrt{x} + 3 = 1 \) by isolating the logarithmic term: subtract 3 from both sides to get \( \ln \sqrt{x} = 1 - 3 \).
Simplify the right side: \( 1 - 3 = -2 \), so the equation becomes \( \ln \sqrt{x} = -2 \).
Recall that \( \sqrt{x} = x^{\frac{1}{2}} \), so rewrite the logarithm as \( \ln x^{\frac{1}{2}} = -2 \).
Use the logarithmic power rule: \( \ln x^{\frac{1}{2}} = \frac{1}{2} \ln x \), so the equation becomes \( \frac{1}{2} \ln x = -2 \).
Multiply both sides by 2 to isolate \( \ln x \): \( \ln x = -4 \). Then, rewrite in exponential form: \( x = e^{-4} \). Finally, check the domain by ensuring \( x > 0 \) since the logarithm is defined only for positive arguments.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Properties of Logarithms

Understanding the properties of logarithms, such as the product, quotient, and power rules, is essential. In this problem, recognizing that ln(√x) can be rewritten as (1/2)ln(x) helps simplify the equation and solve for x.
추천 영상:
5:36
Change of Base Property

Domain of Logarithmic Functions

The domain of a logarithmic function includes only positive real numbers inside the log. When solving, it is crucial to check that the solution values keep the argument of the logarithm positive to ensure the solution is valid.
추천 영상:
5:26
Graphs of Logarithmic Functions

Solving Exponential Equations

After isolating the logarithmic expression, converting the equation from logarithmic to exponential form allows solving for x. For example, if ln(y) = k, then y = e^k, which helps find the exact solution.
추천 영상:
5:47
Solving Exponential Equations Using Logs
관련 실천
교과서 질문

The figure shows the graph of f(x) = ln x. In Exercises 65–74, use transformations of this graph to graph each function. Graph and give equations of the asymptotes. Use the graphs to determine each function's domain and range. g(x) = ln (x+2)

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교과서 질문

In Exercises 64–73, solve each exponential equation. Where necessary, express the solution set in terms of natural or common logarithms and use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution. 2^(4x-2) = 64

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교과서 질문

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. 12(log5x+log5y)2log5(x+1)\(\frac{1}{2}\) \(\left\)( \(\log\)_5 x + \(\log\)_5 y \(\right\)) - 2 \(\log\)_5 (x + 1)

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교과서 질문

The figure shows the graph of f(x) = ln x. In Exercises 65–74, use transformations of this graph to graph each function. Graph and give equations of the asymptotes. Use the graphs to determine each function's domain and range.

h(x) = ln (2x)

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교과서 질문

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. 13[2ln(x+5)lnxln(x24)]\(\frac{1}{3}\) \(\left\)[ 2 \(\ln\)(x + 5) - \(\ln\) x - \(\ln\) (x^2 - 4) \(\right\)]

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교과서 질문

In Exercises 64–73, solve each exponential equation. Where necessary, express the solution set in terms of natural or common logarithms and use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution. 10^x = 7000

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