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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 55

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. h(x)=1+ log₂ x

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Start by understanding the base function: \(f(x) = \log_{2} x\). This function has a vertical asymptote at \(x=0\), a domain of \((0, \infty)\), and a range of \((-\infty, \infty)\).
Next, analyze the given function \(h(x) = 1 + \log_{2} x\). Notice that this is a vertical shift of the base function \(f(x)\) upward by 1 unit.
Since vertical shifts do not affect the vertical asymptote, the vertical asymptote of \(h(x)\) remains at \(x=0\).
The domain of \(h(x)\) is the same as the base function because the logarithm is only defined for positive \(x\), so the domain is \((0, \infty)\).
The range of \(h(x)\) is the range of \(f(x)\) shifted up by 1, so the range is \((-\infty + 1, \infty + 1)\), which simplifies to \((-\infty, \infty)\).

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Key Concepts

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

Graphing Logarithmic Functions

Graphing logarithmic functions involves plotting points based on the logarithm's definition and understanding its shape. For f(x) = log₂ x, the graph passes through (1,0) since log base 2 of 1 is 0, and it increases slowly to the right. Recognizing this base graph is essential before applying transformations.
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Graphs of Logarithmic Functions

Transformations of Functions

Transformations modify the graph of a base function by shifting, stretching, or reflecting it. For h(x) = 1 + log₂ x, the '+1' shifts the entire graph of log₂ x upward by 1 unit. Understanding vertical shifts helps in accurately sketching the new graph and identifying changes in key features like intercepts.
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Domain & Range of Transformed Functions

Vertical Asymptotes and Domain of Logarithmic Functions

Logarithmic functions have vertical asymptotes where the argument equals zero, here at x=0. This asymptote indicates the function approaches negative infinity near this line. The domain consists of all x-values where the argument is positive, so for log₂ x, the domain is (0, ∞). Recognizing this is crucial for graphing and determining the function's range.
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Related Practice
Textbook Question

In Exercises 54–57, use properties of logarithms to condense each logarithmic expression. Write the expression as a single logarithm whose coefficient is 11. log33logx\(\log\)3-3\(\log\) x

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Textbook Question

Use the compound interest formulas A = P (1+ r/n)nt and A =Pert to solve exercises 53-56. Round answers to the nearest cent. Find the accumulated value of an investment of \$10,000 for 5 years at an interest rate of 1.32% if the money is b. compounded quarterly

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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. log2(x+25)=4

Textbook Question

Use the compound interest formulas A = P (1+ r/n)nt and A =Pert to solve exercises 53-56. Round answers to the nearest cent. Find the accumulated value of an investment of \$10,000 for 5 years at an interest rate of 1.32% if the money is d. compounded continuously.

Textbook Question

Use the compound interest formulas A = P (1+ r/n)nt and A =Pert to solve exercises 53-56. Round answers to the nearest cent. Find the accumulated value of an investment of \$10,000 for 5 years at an interest rate of 1.32% if the money is c. compounded monthly.

Textbook Question

Use the compound interest formulas A = P (1+ r/n)nt and A =Pert to solve exercises 53-56. Round answers to the nearest cent. Suppose that you have \$12,000 to invest. Which investment yields the greater return over 3 years: 0.96% compounded monthly or 0.95% compounded continuously?