Math  /  Algebra

QuestionProblems 161-6, Assuming xx and yy are positive, use properties of logarithms to write the expression as a sum or difference of logarithms.
1. log16x\log 16 x
2. ln(3y)ln3lny\ln \left(\frac{3}{y}\right) \ln 3-\ln y
3. ln(e3y5)\ln \left(e^{3} y^{5}\right)
4. log(1000x5)\log \left(1000 x^{5}\right)
5. lnx3y\ln \sqrt{\frac{x^{3}}{y}}
6. log2(x3y2)\log _{2}\left(x^{3} y^{2}\right)

Problems 7 - 12, Assuming x,yx, y, and zz are positive, use properties of logarithms to write the expression as a single logarithm.
7. log264log24\log _{2} 64-\log _{2} 4
8. ln(x+3)+2lnx\ln (x+3)+2 \ln x
9. 4lnx+7lny3lnz4 \ln x+7 \ln y-3 \ln z
10. 13(logx2logy)\frac{1}{3}(\log x-2 \log y)
11. 13[2log(x+1)logxlog(x3)]\frac{1}{3}[2 \log (x+1)-\log x-\log (x-3)]
12. 3[lnx+ln(x2)]4ln(x24)3[\ln x+\ln (x-2)]-4 \ln \left(x^{2}-4\right)

Problems 13 - 16, Use a calculator to evaluate to three decimal places.
13. log418\log _{4} 18
14. log1223\log _{\frac{1}{2}} 23
15. logπ57\log _{\pi} 57
16. log0.816\log _{0.8} 16

Studdy Solution

STEP 1

1. We are using properties of logarithms to manipulate expressions.
2. We assume xx, yy, and zz are positive, allowing us to use logarithmic properties.
3. Calculations for problems 13-16 will be approximated using a calculator.

STEP 2

1. Problems 1-6: Express each logarithmic expression as a sum or difference of logarithms.
2. Problems 7-12: Combine each expression into a single logarithm.
3. Problems 13-16: Evaluate each logarithmic expression to three decimal places using a calculator.

STEP 3

1. Use the product property of logarithms: log16x=log16+logx\log 16x = \log 16 + \log x.
2. Use the quotient property of logarithms: ln(3y)=ln3lny\ln \left(\frac{3}{y}\right) = \ln 3 - \ln y.
3. Use the power property of logarithms: ln(e3y5)=lne3+lny5=3lne+5lny=3+5lny\ln \left(e^{3} y^{5}\right) = \ln e^{3} + \ln y^{5} = 3\ln e + 5\ln y = 3 + 5\ln y.
4. Use the product property: log(1000x5)=log1000+logx5=3+5logx\log \left(1000 x^{5}\right) = \log 1000 + \log x^{5} = 3 + 5\log x.
5. Use the power and quotient properties: lnx3y=ln(x3y)1/2=12(lnx3lny)=32lnx12lny\ln \sqrt{\frac{x^{3}}{y}} = \ln \left(\frac{x^{3}}{y}\right)^{1/2} = \frac{1}{2}(\ln x^{3} - \ln y) = \frac{3}{2}\ln x - \frac{1}{2}\ln y.
6. Use the product property: log2(x3y2)=log2x3+log2y2=3log2x+2log2y\log _{2}\left(x^{3} y^{2}\right) = \log _{2}x^{3} + \log _{2}y^{2} = 3\log _{2}x + 2\log _{2}y.

STEP 4

7. Use the quotient property: log264log24=log2(644)=log216=4\log _{2} 64 - \log _{2} 4 = \log _{2} \left(\frac{64}{4}\right) = \log _{2} 16 = 4.
8. Use the power property: ln(x+3)+2lnx=ln(x+3)+lnx2=ln((x+3)x2)\ln (x+3) + 2 \ln x = \ln (x+3) + \ln x^{2} = \ln \left((x+3)x^{2}\right).
9. Use the power and product properties: 4lnx+7lny3lnz=lnx4+lny7lnz3=ln(x4y7z3)4 \ln x + 7 \ln y - 3 \ln z = \ln x^{4} + \ln y^{7} - \ln z^{3} = \ln \left(\frac{x^{4}y^{7}}{z^{3}}\right).
10. Use the power and quotient properties: 13(logx2logy)=13(logxlogy2)=13log(xy2)=log(x1/3y2/3)\frac{1}{3}(\log x - 2 \log y) = \frac{1}{3}(\log x - \log y^{2}) = \frac{1}{3}\log \left(\frac{x}{y^{2}}\right) = \log \left(\frac{x^{1/3}}{y^{2/3}}\right).
11. Use the power and quotient properties: 13[2log(x+1)logxlog(x3)]=13log((x+1)2x(x3))=log((x+1)2/3(x(x3))1/3)\frac{1}{3}[2 \log (x+1) - \log x - \log (x-3)] = \frac{1}{3}\log \left(\frac{(x+1)^{2}}{x(x-3)}\right) = \log \left(\frac{(x+1)^{2/3}}{(x(x-3))^{1/3}}\right).
12. Use the power and quotient properties: 3[lnx+ln(x2)]4ln(x24)=ln(x(x2))3ln(x24)4=ln((x(x2))3(x24)4)3[\ln x + \ln (x-2)] - 4 \ln \left(x^{2}-4\right) = \ln (x(x-2))^{3} - \ln (x^{2}-4)^{4} = \ln \left(\frac{(x(x-2))^{3}}{(x^{2}-4)^{4}}\right).

STEP 5

13. Use a calculator to evaluate: log4182.085\log _{4} 18 \approx 2.085.
14. Use a calculator to evaluate: log12234.523\log _{\frac{1}{2}} 23 \approx -4.523.
15. Use a calculator to evaluate: logπ572.364\log _{\pi} 57 \approx 2.364.
16. Use a calculator to evaluate: log0.8164.285\log _{0.8} 16 \approx -4.285.

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