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Ch. 4 - Exponential and Logarithmic Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 5, Problem 67

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.
Graph of the natural logarithm function f(x) = ln x with points and vertical asymptote at x = 0.
h(x) = ln (2x)

Verified step by step guidance
1
Start with the base function \(f(x) = \ln x\), which has a vertical asymptote at \(x = 0\), domain \((0, \infty)\), and range \((-\infty, \infty)\).
The function \(h(x) = \ln(2x)\) represents a horizontal scaling of the base function by a factor of \(\frac{1}{2}\) inside the argument of the logarithm.
To find the new vertical asymptote, set the inside of the logarithm equal to zero: \(2x = 0\), which gives \(x = 0\). So the vertical asymptote remains at \(x = 0\).
Determine the domain of \(h(x)\) by solving \(2x > 0\), which simplifies to \(x > 0\). Thus, the domain is \((0, \infty)\), same as the original function.
The range of \(h(x)\) remains \((-\infty, \infty)\) because logarithmic functions are continuous and unbounded vertically regardless of horizontal scaling.

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Key Concepts

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

Logarithmic Functions and Their Graphs

A logarithmic function, such as f(x) = ln(x), is the inverse of an exponential function. Its graph passes through (1,0) and has a vertical asymptote at x = 0. The function is defined only for positive x-values, giving it a domain of (0, ∞) and a range of all real numbers.
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Transformations of Functions

Transformations involve shifting, stretching, compressing, or reflecting a graph. For h(x) = ln(2x), the factor 2 inside the logarithm compresses the graph horizontally by a factor of 1/2. This changes the domain and shifts the vertical asymptote accordingly, affecting the graph's shape and position.
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Asymptotes and Domain of Logarithmic Functions

The vertical asymptote of a logarithmic function occurs where the argument of the log equals zero. For h(x) = ln(2x), the asymptote is at x = 0 since 2x = 0 when x = 0. The domain is all x-values making the argument positive, so here the domain is (0, ∞). Understanding asymptotes helps define where the function is valid.
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Related Practice
Textbook Question

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. 8x=121438^x = 12143

Textbook Question

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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Textbook Question

Solve each logarithmic equation in Exercises 49–92. Be sure to reject any value of x 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. log5 x+log5(4x−1)=1

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Textbook Question

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(x/2)

Textbook Question

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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Textbook Question

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) = 2 ln x