Solve each equation. Give solutions in exact form. See Examples 5–9. log8 (x + 2) + log8 (x + 4) = log8 8
Table of contents
- 0. Review of Algebra4h 18m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations1h 43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 5m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 22m
- 10. Combinatorics & Probability1h 45m
6. Exponential & Logarithmic Functions
Solving Exponential and Logarithmic Equations
Problem 68
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.
Verified step by step guidance1
Start with the given exponential equation: \$8^x = 12143$.
To solve for \(x\), take the natural logarithm (or common logarithm) of both sides to utilize the logarithm property that allows exponents to be brought down: \(\ln(8^x) = \ln(12143)\).
Apply the logarithm power rule: \(x \cdot \ln(8) = \ln(12143)\).
Isolate \(x\) by dividing both sides of the equation by \(\ln(8)\): \(x = \frac{\ln(12143)}{\ln(8)}\).
Use a calculator to evaluate the logarithms and compute the decimal approximation of \(x\), rounding your answer to two decimal places.
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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 solve for the variable.
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Logarithms and Their Properties
Logarithms are the inverse operations of exponentiation. They allow us to solve equations where the variable is an exponent by converting the exponential form into a logarithmic form, making it easier to isolate and solve for the variable.
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Change of Base Property
Using Calculators for Approximations
Calculators can evaluate logarithms and provide decimal approximations of solutions. After expressing the solution in logarithmic form, a calculator helps find a numerical value, often rounded to a specified number of decimal places for practical use.
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Solving Exponential Equations Using Logs
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