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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 65

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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Start by applying the distributive property to the expression: multiply \( \frac{1}{2} \) by each term inside the parentheses. This gives \( \frac{1}{2} \log_5 x + \frac{1}{2} \log_5 y - 2 \log_5 (x + 1) \).
Use the power rule of logarithms, which states that \( a \log_b M = \log_b (M^a) \), to rewrite each term with coefficients as exponents inside the logarithms. So, \( \frac{1}{2} \log_5 x = \log_5 (x^{\frac{1}{2}}) \), \( \frac{1}{2} \log_5 y = \log_5 (y^{\frac{1}{2}}) \), and \( -2 \log_5 (x + 1) = \log_5 ((x + 1)^{-2}) \).
Now, rewrite the expression as the sum and difference of logarithms: \( \log_5 (x^{\frac{1}{2}}) + \log_5 (y^{\frac{1}{2}}) + \log_5 ((x + 1)^{-2}) \).
Apply the product rule of logarithms, which states \( \log_b A + \log_b B = \log_b (AB) \), to combine the first two terms: \( \log_5 (x^{\frac{1}{2}} y^{\frac{1}{2}}) + \log_5 ((x + 1)^{-2}) \).
Finally, use the product rule again to combine all terms into a single logarithm: \( \log_5 \left( x^{\frac{1}{2}} y^{\frac{1}{2}} (x + 1)^{-2} \right) \). This is the condensed form with coefficient 1.

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Key Concepts

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

Properties of Logarithms

Properties of logarithms include rules such as the product rule (log_b(m) + log_b(n) = log_b(mn)), the quotient rule, and the power rule (a·log_b(m) = log_b(m^a)). These allow combining or breaking down logarithmic expressions to simplify or condense them into a single logarithm.
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Condensing Logarithmic Expressions

Condensing logarithmic expressions means rewriting multiple logarithms as one single logarithm. This involves applying the product, quotient, and power rules to combine terms, ensuring the final expression has a coefficient of 1 in front of the logarithm.
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Evaluating Logarithms Without a Calculator

Evaluating logarithms without a calculator requires recognizing values that simplify to known logarithmic results, such as log_b(b) = 1 or log_b(1) = 0. Using properties to rewrite expressions can help identify these values and simplify the expression further.
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Related Practice
Textbook Question

Give the equation of each exponential function whose graph is shown.

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) = 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. 2^(4x-2) = 64

Textbook Question

The figure shows the graph of f(x) = log x. In Exercises 59–64, 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) = 1-log x

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Textbook Question

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

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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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