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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
All textbooksBlitzer 8th EditionCh. 4 - Exponential and Logarithmic FunctionsProblem 127
Chapter 5, Problem 127

In Exercises 125–128, determine whether each statement is true or false. If the statement is false, make the necessary change(s) to produce a true statement.
logb(x3+y3)=3logbx+3logbylog_{b}(x^3+y^3)=3log_{b}x+3log_{b}y

Verified step by step guidance
1
Recall the logarithm property for products: logb(x\(\cdot\)y) = logb(x) + logb(y). This means logarithms turn multiplication inside the log into addition outside the log.
Notice that the expression inside the logarithm on the left side is x3 + y3, which is a sum, not a product. The logarithm property for sums is not the same as for products.
The right side of the equation is 3 \(\log\)_b x + 3 \(\log\)_b y, which can be rewritten using the power rule of logarithms as \(\log\)_b (x^3) + \(\log\)_b (y^3). Using the product rule, this equals \(\log\)_b (x^3 y^3).
Since \(\log\)_b (x^3 + y^3) is not equal to \(\log\)_b (x^3 y^3), the original statement is false.
To make the statement true, replace the sum inside the logarithm with a product: \(\log\)_b (x^3 y^3) = 3 \(\log\)_b x + 3 \(\log\)_b y.

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Key Concepts

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

Properties of Logarithms

Logarithms have specific properties that simplify expressions, such as the product rule: log_b(MN) = log_b M + log_b N, and the power rule: log_b(M^k) = k log_b M. Understanding these rules is essential to manipulate and evaluate logarithmic expressions correctly.
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Change of Base Property

Sum of Cubes vs. Product

The expression x^3 + y^3 is a sum of cubes, which cannot be factored into a simple product of x and y terms. Since logarithm properties apply to products, not sums, recognizing the difference between sums and products is crucial to avoid incorrect application of log rules.
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True or False Statements in Algebra

Determining the truth of algebraic statements involves verifying if the given equality holds for all valid values. If false, one must identify the error and correct it, often by applying the correct algebraic or logarithmic rules, ensuring the statement accurately reflects mathematical principles.
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Introduction to Algebraic Expressions
Related Practice
Textbook Question

In Exercises 125–128, determine whether each statement is true or false. If the statement is false, make the necessary change(s) to produce a true statement.

logb (xy)5 = (logb x + logb y)5

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Textbook Question

Exercises 137–139 will help you prepare for the material covered in the next section. Solve for x: a(x - 2) = b(2x + 3)

Textbook Question

In Exercises 109–112, find the domain of each logarithmic function. f(x) = log[(x+1)/(x-5)]

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Textbook Question

In Exercises 125–128, determine whether each statement is true or false. If the statement is false, make the necessary change(s) to produce a true statement.

log749log77=log749−log77\(\frac{log_749}{log_77}\)=log_749-log_77

Textbook Question

In Exercises 109–112, find the domain of each logarithmic function. f(x) = ln (x² - x − 2)

Textbook Question

If log 3 = A and log 7 = B, find log7 (9) in terms of A and B.