1. How does the power rule for logarithms help when solving logarithms with the form [latex]{\mathrm{log}}_{b}\left(\sqrt[n]{x}\right)[/latex]?
2. What does the change-of-base formula do? Why is it useful when using a calculator?
For the following exercises, expand each logarithm as much as possible. Rewrite each expression as a sum, difference, or product of logs.
3. [latex]{\mathrm{log}}_{b}\left(7x\cdot 2y\right)[/latex]
4. [latex]\mathrm{ln}\left(3ab\cdot 5c\right)[/latex]
5. [latex]{\mathrm{log}}_{b}\left(\frac{13}{17}\right)[/latex]
6. [latex]{\mathrm{log}}_{4}\left(\frac{\text{ }\frac{x}{z}\text{ }}{w}\right)[/latex]
7. [latex]\mathrm{ln}\left(\frac{1}{{4}^{k}}\right)[/latex]
8. [latex]{\mathrm{log}}_{2}\left({y}^{x}\right)[/latex]
For the following exercises, condense to a single logarithm if possible.
9. [latex]\mathrm{ln}\left(7\right)+\mathrm{ln}\left(x\right)+\mathrm{ln}\left(y\right)[/latex]
10. [latex]{\mathrm{log}}_{3}\left(2\right)+{\mathrm{log}}_{3}\left(a\right)+{\mathrm{log}}_{3}\left(11\right)+{\mathrm{log}}_{3}\left(b\right)[/latex]
11. [latex]{\mathrm{log}}_{b}\left(28\right)-{\mathrm{log}}_{b}\left(7\right)[/latex]
12. [latex]\mathrm{ln}\left(a\right)-\mathrm{ln}\left(d\right)-\mathrm{ln}\left(c\right)[/latex]
13. [latex]-{\mathrm{log}}_{b}\left(\frac{1}{7}\right)[/latex]
14. [latex]\frac{1}{3}\mathrm{ln}\left(8\right)[/latex]
For the following exercises, use the properties of logarithms to expand each logarithm as much as possible. Rewrite each expression as a sum, difference, or product of logs.
15. [latex]\mathrm{log}\left(\frac{{x}^{15}{y}^{13}}{{z}^{19}}\right)[/latex]
16. [latex]\mathrm{ln}\left(\frac{{a}^{-2}}{{b}^{-4}{c}^{5}}\right)[/latex]
17. [latex]\mathrm{log}\left(\sqrt{{x}^{3}{y}^{-4}}\right)[/latex]
18. [latex]\mathrm{ln}\left(y\sqrt{\frac{y}{1-y}}\right)[/latex]
19. [latex]\mathrm{log}\left({x}^{2}{y}^{3}\sqrt[3]{{x}^{2}{y}^{5}}\right)[/latex]
For the following exercises, condense each expression to a single logarithm using the properties of logarithms.
20. [latex]\mathrm{log}\left(2{x}^{4}\right)+\mathrm{log}\left(3{x}^{5}\right)[/latex]
21. [latex]\mathrm{ln}\left(6{x}^{9}\right)-\mathrm{ln}\left(3{x}^{2}\right)[/latex]
22. [latex]2\mathrm{log}\left(x\right)+3\mathrm{log}\left(x+1\right)[/latex]
23. [latex]\mathrm{log}\left(x\right)-\frac{1}{2}\mathrm{log}\left(y\right)+3\mathrm{log}\left(z\right)[/latex]
24. [latex]4{\mathrm{log}}_{7}\left(c\right)+\frac{{\mathrm{log}}_{7}\left(a\right)}{3}+\frac{{\mathrm{log}}_{7}\left(b\right)}{3}[/latex]
For the following exercises, rewrite each expression as an equivalent ratio of logs using the indicated base.
25. [latex]{\mathrm{log}}_{7}\left(15\right)[/latex] to base e
26. [latex]{\mathrm{log}}_{14}\left(55.875\right)[/latex] to base 10
For the following exercises, suppose [latex]{\mathrm{log}}_{5}\left(6\right)=a[/latex] and [latex]{\mathrm{log}}_{5}\left(11\right)=b[/latex]. Use the change-of-base formula along with properties of logarithms to rewrite each expression in terms of a and b. Show the steps for solving.
27. [latex]{\mathrm{log}}_{11}\left(5\right)[/latex]
28. [latex]{\mathrm{log}}_{6}\left(55\right)[/latex]
29. [latex]{\mathrm{log}}_{11}\left(\frac{6}{11}\right)[/latex]
For the following exercises, use properties of logarithms to evaluate without using a calculator.
30. [latex]{\mathrm{log}}_{3}\left(\frac{1}{9}\right)-3{\mathrm{log}}_{3}\left(3\right)[/latex]
31. [latex]6{\mathrm{log}}_{8}\left(2\right)+\frac{{\mathrm{log}}_{8}\left(64\right)}{3{\mathrm{log}}_{8}\left(4\right)}[/latex]
32. [latex]2{\mathrm{log}}_{9}\left(3\right)-4{\mathrm{log}}_{9}\left(3\right)+{\mathrm{log}}_{9}\left(\frac{1}{729}\right)[/latex]
For the following exercises, use the change-of-base formula to evaluate each expression as a quotient of natural logs. Use a calculator to approximate each to five decimal places.
33. [latex]{\mathrm{log}}_{3}\left(22\right)[/latex]
34. [latex]{\mathrm{log}}_{8}\left(65\right)[/latex]
35. [latex]{\mathrm{log}}_{6}\left(5.38\right)[/latex]
36. [latex]{\mathrm{log}}_{4}\left(\frac{15}{2}\right)[/latex]
37. [latex]{\mathrm{log}}_{\frac{1}{2}}\left(4.7\right)[/latex]
38. Use the product rule for logarithms to find all x values such that [latex]{\mathrm{log}}_{12}\left(2x+6\right)+{\mathrm{log}}_{12}\left(x+2\right)=2[/latex]. Show the steps for solving.
39. Use the quotient rule for logarithms to find all x values such that [latex]{\mathrm{log}}_{6}\left(x+2\right)-{\mathrm{log}}_{6}\left(x - 3\right)=1[/latex]. Show the steps for solving.
40. Can the power property of logarithms be derived from the power property of exponents using the equation [latex]{b}^{x}=m?[/latex] If not, explain why. If so, show the derivation.
41. Prove that [latex]{\mathrm{log}}_{b}\left(n\right)=\frac{1}{{\mathrm{log}}_{n}\left(b\right)}[/latex] for any positive integers b > 1 and n > 1.
42. Does [latex]{\mathrm{log}}_{81}\left(2401\right)={\mathrm{log}}_{3}\left(7\right)[/latex]? Verify the claim algebraically.
Candela Citations
- Precalculus. Authored by: Jay Abramson, et al.. Provided by: OpenStax. Located at: http://cnx.org/contents/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175. License: CC BY: Attribution. License Terms: Download For Free at : http://cnx.org/contents/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175.