Solve each equation. In Exercises 11–34, give irrational solutions as decimals correct to the nearest thousandth. In Exercises 35-40, give solutions in exact form. 0.05(1.15)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 31
Textbook Question
Solve each equation. In Exercises 11–34, give irrational solutions as decimals correct to the nearest thousandth. In Exercises 35-40, give solutions in exact form. 2(1.05)x + 3 = 10
Verified step by step guidance1
Start by isolating the exponential expression. Subtract 3 from both sides of the equation to get: \$2(1.05)^x = 10 - 3$.
Simplify the right side: \$2(1.05)^x = 7$.
Divide both sides by 2 to isolate the exponential term: \((1.05)^x = \frac{7}{2}\).
To solve for \(x\), take the natural logarithm (ln) of both sides: \(\ln\left((1.05)^x\right) = \ln\left(\frac{7}{2}\right)\).
Use the logarithm power rule to bring down the exponent: \(x \cdot \ln(1.05) = \ln\left(\frac{7}{2}\right)\). Then solve for \(x\) by dividing both sides by \(\ln(1.05)\): \(x = \frac{\ln\left(\frac{7}{2}\right)}{\ln(1.05)}\).
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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, such as 2(1.05)^x + 3 = 10. Solving these requires isolating the exponential expression before applying logarithms or other methods to find the variable.
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Isolating the Exponential Term
To solve an exponential equation, first isolate the term containing the exponent by performing inverse operations like subtraction and division. For example, subtract 3 and then divide by 2 to get (1.05)^x alone.
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Using Logarithms to Solve for the Exponent
Once the exponential term is isolated, apply logarithms (common or natural) to both sides to bring the exponent down. This allows solving for x by using the property log(a^x) = x log(a), enabling calculation of the variable.
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