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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 37

Solve each exponential equation in Exercises 23–48. Express the solution set in terms of natural logarithms or common logarithms. Then use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution. 7(x+2)=410

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Start with the given exponential equation: \$7^{(x+2)} = 410$.
To solve for \(x\), take the natural logarithm (or common logarithm) of both sides to utilize the property that \(\ln(a^b) = b \ln(a)\): \(\ln\left(7^{(x+2)}\right) = \ln(410)\).
Apply the logarithm power rule to bring down the exponent: \((x+2) \ln(7) = \ln(410)\).
Isolate the term with \(x\) by dividing both sides by \(\ln(7)\): \(x + 2 = \frac{\ln(410)}{\ln(7)}\).
Finally, solve for \(x\) by subtracting 2 from both sides: \(x = \frac{\ln(410)}{\ln(7)} - 2\).

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Key Concepts

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

Exponential Equations

An exponential equation is one in which the variable appears in the exponent. Solving such equations often involves rewriting the equation to isolate the exponential expression and then applying logarithms to both sides to solve for the variable.
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Logarithms (Natural and Common)

Logarithms are the inverse operations of exponentiation. The natural logarithm (ln) uses base e, while the common logarithm (log) uses base 10. Applying logarithms allows us to solve for variables in exponents by converting the equation into a linear form.
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Graphs of Common Functions

Using a Calculator for Decimal Approximations

After expressing the solution in logarithmic form, a calculator is used to find decimal approximations. This step involves evaluating logarithmic expressions and rounding the result to the desired decimal places, ensuring practical and understandable answers.
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Solving Exponential Equations Using Logs
Related Practice
Textbook Question

In Exercises 39–40, graph f and g in the same rectangular coordinate system. Use transformations of the graph of f to obtain the graph of g. Graph and give equations of all asymptotes. Use the graphs to determine each function's domain and range. f(x) = log x and g(x) = - log (x+3)

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Textbook Question

Use properties of logarithms to expand each logarithmic expression as much as possible. Where possible, evaluate logarithmic expressions without using a calculator. ln(x3x2+1(x+1)4)\(\ln\) \(\left\)( \(\frac{x^3 \sqrt{x^2 + 1}\)}{(x + 1)^4} \(\right\))

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Textbook Question

Evaluate each expression without using a calculator. log4 1

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Textbook Question

The figure shows the graph of f(x) = ex. In Exercises 35-46, use transformations of this graph to graph each function. Be sure to give equations of the asymptotes. Use the graphs to determine graphs. each function's domain and range. If applicable, use a graphing utility to confirm your hand-drawn g(x) = ex+2

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Textbook Question

In Exercises 36–38, begin by graphing f(x) = log2 x Then use transformations of this graph to graph the given function. What is the graph's x-intercept? What is the vertical asymptote? Use the graphs to determine each function's domain and range. g(x) = log2 (x-2)

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Textbook Question

Solve each exponential equation in Exercises 23–48. Express the solution set in terms of natural logarithms or common logarithms. Then use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution. 70.3x=813

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