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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 51

Graph functions f and g in the same rectangular coordinate system. Graph and give equations of all asymptotes. If applicable, use a graphing utility to confirm your hand-drawn graphs. f(x) = (½)x and g(x) = (½)x-1 + 1

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Identify the base functions and their transformations. The function \(f(x) = (\frac{1}{2})^x\) is an exponential decay function with base \(\frac{1}{2}\), and \(g(x) = (\frac{1}{2})^{x-1} + 1\) is a horizontal shift and vertical shift of \(f(x)\).
Determine the asymptotes for each function. For \(f(x)\), the horizontal asymptote is \(y = 0\) because as \(x \to \infty\), \((\frac{1}{2})^x \to 0\). For \(g(x)\), the vertical shift by \(+1\) moves the horizontal asymptote to \(y = 1\).
Graph \(f(x)\) by plotting key points such as \(f(0) = 1\), \(f(1) = \frac{1}{2}\), and \(f(-1) = 2\), and sketch the curve approaching the asymptote \(y=0\) as \(x\) increases.
Graph \(g(x)\) by applying the horizontal shift of 1 unit to the right (replace \(x\) by \(x-1\)) and then shifting the entire graph up by 1 unit. Plot points like \(g(1) = 1 + (\frac{1}{2})^0 = 2\), \(g(2) = 1 + (\frac{1}{2})^1 = 1.5\), and \(g(0) = 1 + (\frac{1}{2})^{-1} = 3\) to help sketch the curve.
Confirm the graphs and asymptotes using a graphing utility by entering both functions and observing their behavior, ensuring the asymptotes \(y=0\) for \(f(x)\) and \(y=1\) for \(g(x)\) are correctly represented.

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Key Concepts

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

Exponential Functions

Exponential functions have the form f(x) = a^x, where the base a is a positive constant. They exhibit rapid growth or decay depending on whether a is greater or less than 1. Understanding their shape and behavior is essential for graphing and comparing functions like f(x) = (1/2)^x and g(x) = (1/2)^{x-1} + 1.
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Exponential Functions

Transformations of Functions

Function transformations include shifts, stretches, and reflections that alter the graph's position or shape. For example, g(x) = (1/2)^{x-1} + 1 is a horizontal shift right by 1 unit and a vertical shift up by 1 unit of f(x) = (1/2)^x. Recognizing these helps in sketching graphs and understanding their relationships.
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Domain & Range of Transformed Functions

Asymptotes of Functions

Asymptotes are lines that a graph approaches but never touches. Exponential functions often have horizontal asymptotes representing limits as x approaches infinity or negative infinity. Identifying and writing equations of asymptotes is crucial for accurately graphing and analyzing functions like f and g.
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Related Practice
Textbook Question

Begin by graphing f(x) = log₂ x. Then use transformations of this graph to graph the given function. What is the vertical asymptote? Use the graphs to determine each function's domain and range. g(x) = log₂ (x + 1)

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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. log x + 3 log y

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Textbook Question

In Exercises 50–53, use properties of logarithms to expand each logarithmic expression as much as possible. Where possible, evaluate logarithmic expressions without using a calculator. log4(x64)\(\log\)_4\(\left\)(\(\frac{\sqrt{x}\)}{64}\(\right\))

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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. log4(x+5)=3

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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. ln x=2

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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. (1/2)ln x + ln y

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