In Exercises 74–79, solve each logarithmic equation. log4 (2x+1) = log4 (x-3) + log4 (x+5)
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 81
Textbook Question
Solve each equation. Give solutions in exact form. log2 (log2 x) = 1
Verified step by step guidance1
Start by understanding the equation: \(\log_2 (\log_2 x) = 1\). This means the logarithm base 2 of another logarithm base 2 of \(x\) equals 1.
Rewrite the equation by setting an inner variable: let \(y = \log_2 x\). Then the equation becomes \(\log_2 y = 1\).
Solve for \(y\) by converting the logarithmic equation to its exponential form: \(y = 2^1\).
Substitute back \(y = \log_2 x\) to get \(\log_2 x = 2\).
Solve for \(x\) by rewriting the logarithmic equation in exponential form: \(x = 2^2\).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Properties of Logarithms
Understanding the properties of logarithms, such as the definition log_b(a) = c means b^c = a, is essential. This allows you to rewrite logarithmic equations into exponential form to solve for the variable.
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Domain Restrictions of Logarithmic Functions
Logarithmic functions are only defined for positive arguments. When solving nested logarithmic equations like log_2(log_2 x), you must ensure both the inner and outer logarithm arguments are positive to find valid solutions.
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Domain Restrictions of Composed Functions
Solving Nested Logarithmic Equations
Solving equations with nested logarithms involves working from the outer logarithm inward. First, isolate the inner logarithm, then solve the resulting simpler logarithmic or exponential equation step-by-step.
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