{"id":312,"date":"2026-02-02T16:57:09","date_gmt":"2026-02-02T16:57:09","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/?post_type=chapter&#038;p=312"},"modified":"2026-02-02T18:23:11","modified_gmt":"2026-02-02T18:23:11","slug":"exponential-and-logarithmic-equations-get-stronger-answer-key","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/chapter\/exponential-and-logarithmic-equations-get-stronger-answer-key\/","title":{"raw":"Exponential and Logarithmic Equations Get Stronger Answer Key","rendered":"Exponential and Logarithmic Equations Get Stronger Answer Key"},"content":{"raw":"<h1>Exponential and Logarithmic Equations: Get Stronger Key<\/h1>\r\n<h2>Logarithmic Properties<\/h2>\r\n3.\u00a0[latex]{\\mathrm{log}}_{b}\\left(2\\right)+{\\mathrm{log}}_{b}\\left(7\\right)+{\\mathrm{log}}_{b}\\left(x\\right)+{\\mathrm{log}}_{b}\\left(y\\right)[\/latex]\r\n\r\n5.\u00a0[latex]{\\mathrm{log}}_{b}\\left(13\\right)-{\\mathrm{log}}_{b}\\left(17\\right)[\/latex]\r\n\r\n7.\u00a0[latex]-k\\mathrm{ln}\\left(4\\right)[\/latex]\r\n\r\n9.\u00a0[latex]\\mathrm{ln}\\left(7xy\\right)[\/latex]\r\n\r\n11.\u00a0[latex]{\\mathrm{log}}_{b}\\left(4\\right)[\/latex]\r\n\r\n13.\u00a0[latex]{\\text{log}}_{b}\\left(7\\right)[\/latex]\r\n\r\n15.\u00a0[latex]15\\mathrm{log}\\left(x\\right)+13\\mathrm{log}\\left(y\\right)-19\\mathrm{log}\\left(z\\right)[\/latex]\r\n\r\n17.\u00a0[latex]\\frac{3}{2}\\mathrm{log}\\left(x\\right)-2\\mathrm{log}\\left(y\\right)[\/latex]\r\n\r\n19.\u00a0[latex]\\frac{8}{3}\\mathrm{log}\\left(x\\right)+\\frac{14}{3}\\mathrm{log}\\left(y\\right)[\/latex]\r\n\r\n21.\u00a0[latex]\\mathrm{ln}\\left(2{x}^{7}\\right)[\/latex]\r\n\r\n23.\u00a0[latex]\\mathrm{log}\\left(\\frac{x{z}^{3}}{\\sqrt{y}}\\right)[\/latex]\r\n\r\n27.\u00a0[latex]{\\mathrm{log}}_{11}\\left(5\\right)=\\frac{{\\mathrm{log}}_{5}\\left(5\\right)}{{\\mathrm{log}}_{5}\\left(11\\right)}=\\frac{1}{b}[\/latex]\r\n\r\n29.\u00a0[latex]{\\mathrm{log}}_{11}\\left(\\frac{6}{11}\\right)=\\frac{{\\mathrm{log}}_{5}\\left(\\frac{6}{11}\\right)}{{\\mathrm{log}}_{5}\\left(11\\right)}=\\frac{{\\mathrm{log}}_{5}\\left(6\\right)-{\\mathrm{log}}_{5}\\left(11\\right)}{{\\mathrm{log}}_{5}\\left(11\\right)}=\\frac{a-b}{b}=\\frac{a}{b}-1[\/latex]\r\n\r\n31.\u00a03\r\n\r\n33. 2.81359\r\n\r\n35. 0.93913\r\n\r\n37. \u20132.23266\r\n\r\n39.\u00a0<em>x\u00a0<\/em>= 4; By the quotient rule: [latex]{\\mathrm{log}}_{6}\\left(x+2\\right)-{\\mathrm{log}}_{6}\\left(x - 3\\right)={\\mathrm{log}}_{6}\\left(\\frac{x+2}{x - 3}\\right)=1[\/latex].\r\n<p id=\"fs-id1165135195640\">Rewriting as an exponential equation and solving for <em>x<\/em>:<\/p>\r\n<p id=\"fs-id1165134316855\">[latex]\\begin{cases}{6}^{1}\\hfill &amp; =\\frac{x+2}{x - 3}\\hfill \\\\ 0\\hfill &amp; =\\frac{x+2}{x - 3}-6\\hfill \\\\ 0\\hfill &amp; =\\frac{x+2}{x - 3}-\\frac{6\\left(x - 3\\right)}{\\left(x - 3\\right)}\\hfill \\\\ 0\\hfill &amp; =\\frac{x+2 - 6x+18}{x - 3}\\hfill \\\\ 0\\hfill &amp; =\\frac{x - 4}{x - 3}\\hfill \\\\ \\text{ }x\\hfill &amp; =4\\hfill \\end{cases}[\/latex]<\/p>\r\n<p id=\"fs-id1165135451281\">Checking, we find that [latex]{\\mathrm{log}}_{6}\\left(4+2\\right)-{\\mathrm{log}}_{6}\\left(4 - 3\\right)={\\mathrm{log}}_{6}\\left(6\\right)-{\\mathrm{log}}_{6}\\left(1\\right)[\/latex] is defined, so <em>x\u00a0<\/em>= 4.<\/p>\r\n\r\n<h2>Exponential and Logarithmic Equations<\/h2>\r\n2. An extraneous solution occurs when solving the equation results in a value that does not satisfy the original equation. It can be recognized by substituting the solution back into the original equation and seeing that it makes the equation false or violates a domain restriction (for example, giving a negative input to a logarithm or an even root, or causing division by zero).\r\n\r\n3.\u00a0The one-to-one property can be used if both sides of the equation can be rewritten as a single logarithm with the same base. If so, the arguments can be set equal to each other, and the resulting equation can be solved algebraically. The one-to-one property cannot be used when each side of the equation cannot be rewritten as a single logarithm with the same base.\r\n\r\n5.\u00a0[latex]x=-\\frac{1}{3}[\/latex]\r\n\r\n7. <em>n\u00a0<\/em>= \u20131\r\n\r\n9.\u00a0[latex]b=\\frac{6}{5}[\/latex]\r\n\r\n11. <em>x\u00a0<\/em>= 10\r\n\r\n13.\u00a0No solution\r\n\r\n15.\u00a0[latex]p=\\mathrm{log}\\left(\\frac{17}{8}\\right)-7[\/latex]\r\n\r\n21.\u00a0[latex]x=\\mathrm{ln}12[\/latex]\r\n\r\n27.\u00a0[latex]x=\\mathrm{ln}\\left(3\\right)[\/latex]\r\n\r\n31. <em>n\u00a0<\/em>= 49\r\n\r\n33.\u00a0[latex]k=\\frac{1}{36}[\/latex]\r\n\r\n35.\u00a0[latex]x=\\frac{9-e}{8}[\/latex]\r\n\r\n37. <em>n\u00a0<\/em>= 1\r\n\r\n39.\u00a0No solution\r\n\r\n41.\u00a0No solution\r\n\r\n43.\u00a0[latex]x=\\pm \\frac{10}{3}[\/latex]\r\n\r\n51. <em>x\u00a0<\/em>= 9\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005327\/CNX_PreCalc_Figure_04_06_201.jpg\" alt=\"Graph of log_9(x)-5=y and y=-4.\" \/>\r\n\r\n53.\u00a0[latex]x=\\frac{{e}^{2}}{3}\\approx 2.5[\/latex]\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_203.jpg\" alt=\"Graph of ln(3x)=y and y=2.\" \/>\r\n\r\n55. <em>x\u00a0<\/em>= \u20135\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_205.jpg\" alt=\"Graph of log(4)+log(-5x)=y and y=2.\" \/>\r\n\r\n57.\u00a0[latex]x=\\frac{e+10}{4}\\approx 3.2[\/latex]\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_207.jpg\" alt=\"Graph of ln(4x-10)-6=y and y=-5.\" \/>\r\n\r\n59.\u00a0No solution\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_209.jpg\" alt=\"Graph of log_11(-2x^2-7x)=y and y=log_11(x-2).\" \/>\r\n\r\n61.\u00a0[latex]x=\\frac{11}{5}\\approx 2.2[\/latex]\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005329\/CNX_PreCalc_Figure_04_06_211.jpg\" alt=\"Graph of log_9(3-x)=y and y=log_9(4x-8).\" \/>\r\n\r\n65.\u00a0about $27,710.24\r\n\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005329\/CNX_PreCalc_Figure_04_06_215.jpg\" alt=\"Graph of f(x)=6500e^(0.0725x) with the labeled point at (20, 27710.24).\" \/>\r\n\r\n67.\u00a0about 5 years\r\n\r\n69.\u00a0[latex]\\frac{\\mathrm{ln}\\left(17\\right)}{5}\\approx 0.567[\/latex]\r\n\r\n71.\u00a0[latex]x=\\frac{\\mathrm{log}\\left(38\\right)+5\\mathrm{log}\\left(3\\right)\\text{ }}{4\\mathrm{log}\\left(3\\right)}\\approx 2.078[\/latex]\r\n\r\n73.\u00a0[latex]x\\approx 2.2401[\/latex]\r\n\r\n75.\u00a0[latex]x\\approx -44655.7143[\/latex]\r\n\r\n77.\u00a0about 5.83\r\n\r\n81.\u00a0[latex]t=\\mathrm{ln}\\left({\\left(\\frac{T-{T}_{s}}{{T}_{0}-{T}_{s}}\\right)}^{-\\frac{1}{k}}\\right)[\/latex]\r\n<h2>Exponential and Logarithmic Models<\/h2>\r\n1. Half-life is a measure of decay and is thus associated with exponential decay models. The half-life of a substance or quantity is the amount of time it takes for half of the initial amount of that substance or quantity to decay.\r\n\r\n7.\u00a0[latex]f\\left(0\\right)\\approx 16.7[\/latex]; The amount initially present is about 16.7 units.\r\n\r\n9.\u00a0150\r\n\r\n11. exponential; [latex]f\\left(x\\right)={1.2}^{x}[\/latex]\r\n\r\n13. logarithmic\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005332\/CNX_PreCalc_Figure_04_07_201.jpg\" alt=\"Graph of the question\u2019s table.\" \/>\r\n\r\n15. logarithmic\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005332\/CNX_PreCalc_Figure_04_07_203.jpg\" alt=\"Graph of the question\u2019s table.\" \/>\r\n\r\n17.\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005333\/CNX_PreCalc_Figure_04_07_205.jpg\" alt=\"Graph of P(t)=1000\/(1+9e^(-0.6t))\" \/>\r\n\r\n21. about 7.3 years\r\n\r\n23. 4 half-lives; 8.18 minutes\r\n\r\n25. [latex]\\begin{cases}\\text{ }M=\\frac{2}{3}\\mathrm{log}\\left(\\frac{S}{{S}_{0}}\\right)\\hfill \\\\ \\mathrm{log}\\left(\\frac{S}{{S}_{0}}\\right)=\\frac{3}{2}M\\hfill \\\\ \\text{ }\\frac{S}{{S}_{0}}={10}^{\\frac{3M}{2}}\\hfill \\\\ \\text{ }S={S}_{0}{10}^{\\frac{3M}{2}}\\hfill \\end{cases}\/\/[\/latex]\r\n\r\n28. 2 hours.\r\n\r\n29.\u00a0[latex]A=125{e}^{\\left(-0.3567t\\right)};A\\approx 43[\/latex] mg\r\n\r\n31.\u00a0about 60 days\r\n\r\n32. [latex]A(t)=0.5(0.9885)^t[\/latex]. After 60 days, [latex]A(60)\\approx 0.3[\/latex] grams.\r\n\r\n33.\u00a0[latex]f\\left(t\\right)=250{e}^{\\left(-0.00914t\\right)}[\/latex]; half-life: about [latex]\\text{76}[\/latex] minutes\r\n\r\n35.\u00a0[latex]r\\approx -0.0667[\/latex], So the hourly decay rate is about 6.67%\r\n\r\n37.\u00a0[latex]f\\left(t\\right)=1350{e}^{\\left(0.03466t\\right)}[\/latex]; after 3 hours: [latex]P\\left(180\\right)\\approx 691,200[\/latex]\r\n\r\n40.\u00a0 [latex]T(t)=69+31e^{\\left(\\frac{1}{15}\\ln\\left(\\frac{26}{31}\\right)\\right)t}[\/latex].\r\n\r\n41.\u00a0about 88 minutes\r\n<h2>Fitting Exponential Models to Data<\/h2>\r\n4. A scatterplot that is best described by a logarithmic model would show a rapid increase or decrease at first, followed by a gradual leveling off as the input values increase. The data points would form a curve that rises (or falls) quickly and then flattens.\r\n\r\n6. E\r\n\r\n7. C\r\n\r\n8. A\r\n\r\n9. B\r\n\r\n10. D\r\n\r\n11.\u00a0[latex]P\\left(0\\right)=22[\/latex] ; 175\r\n\r\n13.\u00a0[latex]p\\approx 2.67[\/latex]\r\n\r\n16. <img class=\"alignnone  wp-image-315\" src=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM.png\" alt=\"The graph is a logistic growth function. It increases slowly at first, then more rapidly, and finally levels off around 27 months near the max capacity of 68.\r\n\r\nFor small x-values near 0, the y-values are close to 0. Around x equals 6, the y-value is about 15. Around x equals 12, the y-value is about 45. Around x equals 18, the y-value is about 60. \" width=\"249\" height=\"204\" \/>\r\n\r\n17. 4 koi\r\n\r\n18. 6.8 months\r\n\r\n20. <img class=\"alignnone  wp-image-316\" src=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM.png\" alt=\"The graph is a logistic growth function. It increases slowly at first, then more rapidly, and then levels off as x increases.\r\n\r\nThe graph has approximate values:\r\nAt x equals 0, y is close to 0.\r\nAt x equals 5, y is about 80.\r\nAt x equals 10, y is about 400.\r\nAt x equals 15, y is about 550.\r\nAt x equals 20, y is about 580.\r\n\r\nThe graph approaches a horizontal asymptote at y equals 588 but does not reach it.\" width=\"252\" height=\"191\" \/>\r\n\r\n21. 10 wolves\r\n\r\n23.\u00a0about 5.4 years.\r\n\r\n25.\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010839\/CNX_PreCalc_Figure_04_08_2102.jpg\" alt=\"Graph of the table\u2019s values.\" \/>\r\n\r\n26. [latex]f(x)\\approx 795(1.415)^x[\/latex]<span id=\"fs-id1436308\"><\/span>\r\n\r\n31.\u00a0[latex]f\\left(x\\right)=731.92{\\left(0.738\\right)}^{x}[\/latex]\r\n\r\n35.\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010839\/CNX_PreCalc_Figure_04_08_2162.jpg\" alt=\"Graph of the table\u2019s values.\" \/>\r\n\r\n36. [latex]y\\approx 5.06+1.93\\ln(x)[\/latex]\r\n\r\n37.\u00a0[latex]f\\left(10\\right)\\approx 9.5[\/latex]\r\n\r\n40. <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010840\/CNX_PreCalc_Figure_04_08_2202.jpg\" alt=\"Graph of a scattered plot with an estimation line.\" \/>\r\n\r\n41.\u00a0[latex]f\\left(x\\right)=7.544 - 2.268\\mathrm{ln}\\left(x\\right)[\/latex]\r\n\r\n45.\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010840\/CNX_PreCalc_Figure_04_08_2222.jpg\" alt=\"Graph of the table\u2019s values.\" \/>\r\n\r\n46. [latex]y\\approx 26.91-24.20e^{-0.264x}[\/latex]\r\n\r\n51.\u00a0[latex]f\\left(x\\right)=\\frac{136.068}{1+10.324{e}^{-0.480x}}[\/latex]\r\n\r\n53.\u00a0about 136","rendered":"<h1>Exponential and Logarithmic Equations: Get Stronger Key<\/h1>\n<h2>Logarithmic Properties<\/h2>\n<p>3.\u00a0[latex]{\\mathrm{log}}_{b}\\left(2\\right)+{\\mathrm{log}}_{b}\\left(7\\right)+{\\mathrm{log}}_{b}\\left(x\\right)+{\\mathrm{log}}_{b}\\left(y\\right)[\/latex]<\/p>\n<p>5.\u00a0[latex]{\\mathrm{log}}_{b}\\left(13\\right)-{\\mathrm{log}}_{b}\\left(17\\right)[\/latex]<\/p>\n<p>7.\u00a0[latex]-k\\mathrm{ln}\\left(4\\right)[\/latex]<\/p>\n<p>9.\u00a0[latex]\\mathrm{ln}\\left(7xy\\right)[\/latex]<\/p>\n<p>11.\u00a0[latex]{\\mathrm{log}}_{b}\\left(4\\right)[\/latex]<\/p>\n<p>13.\u00a0[latex]{\\text{log}}_{b}\\left(7\\right)[\/latex]<\/p>\n<p>15.\u00a0[latex]15\\mathrm{log}\\left(x\\right)+13\\mathrm{log}\\left(y\\right)-19\\mathrm{log}\\left(z\\right)[\/latex]<\/p>\n<p>17.\u00a0[latex]\\frac{3}{2}\\mathrm{log}\\left(x\\right)-2\\mathrm{log}\\left(y\\right)[\/latex]<\/p>\n<p>19.\u00a0[latex]\\frac{8}{3}\\mathrm{log}\\left(x\\right)+\\frac{14}{3}\\mathrm{log}\\left(y\\right)[\/latex]<\/p>\n<p>21.\u00a0[latex]\\mathrm{ln}\\left(2{x}^{7}\\right)[\/latex]<\/p>\n<p>23.\u00a0[latex]\\mathrm{log}\\left(\\frac{x{z}^{3}}{\\sqrt{y}}\\right)[\/latex]<\/p>\n<p>27.\u00a0[latex]{\\mathrm{log}}_{11}\\left(5\\right)=\\frac{{\\mathrm{log}}_{5}\\left(5\\right)}{{\\mathrm{log}}_{5}\\left(11\\right)}=\\frac{1}{b}[\/latex]<\/p>\n<p>29.\u00a0[latex]{\\mathrm{log}}_{11}\\left(\\frac{6}{11}\\right)=\\frac{{\\mathrm{log}}_{5}\\left(\\frac{6}{11}\\right)}{{\\mathrm{log}}_{5}\\left(11\\right)}=\\frac{{\\mathrm{log}}_{5}\\left(6\\right)-{\\mathrm{log}}_{5}\\left(11\\right)}{{\\mathrm{log}}_{5}\\left(11\\right)}=\\frac{a-b}{b}=\\frac{a}{b}-1[\/latex]<\/p>\n<p>31.\u00a03<\/p>\n<p>33. 2.81359<\/p>\n<p>35. 0.93913<\/p>\n<p>37. \u20132.23266<\/p>\n<p>39.\u00a0<em>x\u00a0<\/em>= 4; By the quotient rule: [latex]{\\mathrm{log}}_{6}\\left(x+2\\right)-{\\mathrm{log}}_{6}\\left(x - 3\\right)={\\mathrm{log}}_{6}\\left(\\frac{x+2}{x - 3}\\right)=1[\/latex].<\/p>\n<p id=\"fs-id1165135195640\">Rewriting as an exponential equation and solving for <em>x<\/em>:<\/p>\n<p id=\"fs-id1165134316855\">[latex]\\begin{cases}{6}^{1}\\hfill & =\\frac{x+2}{x - 3}\\hfill \\\\ 0\\hfill & =\\frac{x+2}{x - 3}-6\\hfill \\\\ 0\\hfill & =\\frac{x+2}{x - 3}-\\frac{6\\left(x - 3\\right)}{\\left(x - 3\\right)}\\hfill \\\\ 0\\hfill & =\\frac{x+2 - 6x+18}{x - 3}\\hfill \\\\ 0\\hfill & =\\frac{x - 4}{x - 3}\\hfill \\\\ \\text{ }x\\hfill & =4\\hfill \\end{cases}[\/latex]<\/p>\n<p id=\"fs-id1165135451281\">Checking, we find that [latex]{\\mathrm{log}}_{6}\\left(4+2\\right)-{\\mathrm{log}}_{6}\\left(4 - 3\\right)={\\mathrm{log}}_{6}\\left(6\\right)-{\\mathrm{log}}_{6}\\left(1\\right)[\/latex] is defined, so <em>x\u00a0<\/em>= 4.<\/p>\n<h2>Exponential and Logarithmic Equations<\/h2>\n<p>2. An extraneous solution occurs when solving the equation results in a value that does not satisfy the original equation. It can be recognized by substituting the solution back into the original equation and seeing that it makes the equation false or violates a domain restriction (for example, giving a negative input to a logarithm or an even root, or causing division by zero).<\/p>\n<p>3.\u00a0The one-to-one property can be used if both sides of the equation can be rewritten as a single logarithm with the same base. If so, the arguments can be set equal to each other, and the resulting equation can be solved algebraically. The one-to-one property cannot be used when each side of the equation cannot be rewritten as a single logarithm with the same base.<\/p>\n<p>5.\u00a0[latex]x=-\\frac{1}{3}[\/latex]<\/p>\n<p>7. <em>n\u00a0<\/em>= \u20131<\/p>\n<p>9.\u00a0[latex]b=\\frac{6}{5}[\/latex]<\/p>\n<p>11. <em>x\u00a0<\/em>= 10<\/p>\n<p>13.\u00a0No solution<\/p>\n<p>15.\u00a0[latex]p=\\mathrm{log}\\left(\\frac{17}{8}\\right)-7[\/latex]<\/p>\n<p>21.\u00a0[latex]x=\\mathrm{ln}12[\/latex]<\/p>\n<p>27.\u00a0[latex]x=\\mathrm{ln}\\left(3\\right)[\/latex]<\/p>\n<p>31. <em>n\u00a0<\/em>= 49<\/p>\n<p>33.\u00a0[latex]k=\\frac{1}{36}[\/latex]<\/p>\n<p>35.\u00a0[latex]x=\\frac{9-e}{8}[\/latex]<\/p>\n<p>37. <em>n\u00a0<\/em>= 1<\/p>\n<p>39.\u00a0No solution<\/p>\n<p>41.\u00a0No solution<\/p>\n<p>43.\u00a0[latex]x=\\pm \\frac{10}{3}[\/latex]<\/p>\n<p>51. <em>x\u00a0<\/em>= 9<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005327\/CNX_PreCalc_Figure_04_06_201.jpg\" alt=\"Graph of log_9(x)-5=y and y=-4.\" \/><\/p>\n<p>53.\u00a0[latex]x=\\frac{{e}^{2}}{3}\\approx 2.5[\/latex]<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_203.jpg\" alt=\"Graph of ln(3x)=y and y=2.\" \/><\/p>\n<p>55. <em>x\u00a0<\/em>= \u20135<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_205.jpg\" alt=\"Graph of log(4)+log(-5x)=y and y=2.\" \/><\/p>\n<p>57.\u00a0[latex]x=\\frac{e+10}{4}\\approx 3.2[\/latex]<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_207.jpg\" alt=\"Graph of ln(4x-10)-6=y and y=-5.\" \/><\/p>\n<p>59.\u00a0No solution<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005328\/CNX_PreCalc_Figure_04_06_209.jpg\" alt=\"Graph of log_11(-2x^2-7x)=y and y=log_11(x-2).\" \/><\/p>\n<p>61.\u00a0[latex]x=\\frac{11}{5}\\approx 2.2[\/latex]<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005329\/CNX_PreCalc_Figure_04_06_211.jpg\" alt=\"Graph of log_9(3-x)=y and y=log_9(4x-8).\" \/><\/p>\n<p>65.\u00a0about $27,710.24<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005329\/CNX_PreCalc_Figure_04_06_215.jpg\" alt=\"Graph of f(x)=6500e^(0.0725x) with the labeled point at (20, 27710.24).\" \/><\/p>\n<p>67.\u00a0about 5 years<\/p>\n<p>69.\u00a0[latex]\\frac{\\mathrm{ln}\\left(17\\right)}{5}\\approx 0.567[\/latex]<\/p>\n<p>71.\u00a0[latex]x=\\frac{\\mathrm{log}\\left(38\\right)+5\\mathrm{log}\\left(3\\right)\\text{ }}{4\\mathrm{log}\\left(3\\right)}\\approx 2.078[\/latex]<\/p>\n<p>73.\u00a0[latex]x\\approx 2.2401[\/latex]<\/p>\n<p>75.\u00a0[latex]x\\approx -44655.7143[\/latex]<\/p>\n<p>77.\u00a0about 5.83<\/p>\n<p>81.\u00a0[latex]t=\\mathrm{ln}\\left({\\left(\\frac{T-{T}_{s}}{{T}_{0}-{T}_{s}}\\right)}^{-\\frac{1}{k}}\\right)[\/latex]<\/p>\n<h2>Exponential and Logarithmic Models<\/h2>\n<p>1. Half-life is a measure of decay and is thus associated with exponential decay models. The half-life of a substance or quantity is the amount of time it takes for half of the initial amount of that substance or quantity to decay.<\/p>\n<p>7.\u00a0[latex]f\\left(0\\right)\\approx 16.7[\/latex]; The amount initially present is about 16.7 units.<\/p>\n<p>9.\u00a0150<\/p>\n<p>11. exponential; [latex]f\\left(x\\right)={1.2}^{x}[\/latex]<\/p>\n<p>13. logarithmic<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005332\/CNX_PreCalc_Figure_04_07_201.jpg\" alt=\"Graph of the question\u2019s table.\" \/><\/p>\n<p>15. logarithmic<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005332\/CNX_PreCalc_Figure_04_07_203.jpg\" alt=\"Graph of the question\u2019s table.\" \/><\/p>\n<p>17.<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03005333\/CNX_PreCalc_Figure_04_07_205.jpg\" alt=\"Graph of P(t)=1000\/(1+9e^(-0.6t))\" \/><\/p>\n<p>21. about 7.3 years<\/p>\n<p>23. 4 half-lives; 8.18 minutes<\/p>\n<p>25. [latex]\\begin{cases}\\text{ }M=\\frac{2}{3}\\mathrm{log}\\left(\\frac{S}{{S}_{0}}\\right)\\hfill \\\\ \\mathrm{log}\\left(\\frac{S}{{S}_{0}}\\right)=\\frac{3}{2}M\\hfill \\\\ \\text{ }\\frac{S}{{S}_{0}}={10}^{\\frac{3M}{2}}\\hfill \\\\ \\text{ }S={S}_{0}{10}^{\\frac{3M}{2}}\\hfill \\end{cases}\/\/[\/latex]<\/p>\n<p>28. 2 hours.<\/p>\n<p>29.\u00a0[latex]A=125{e}^{\\left(-0.3567t\\right)};A\\approx 43[\/latex] mg<\/p>\n<p>31.\u00a0about 60 days<\/p>\n<p>32. [latex]A(t)=0.5(0.9885)^t[\/latex]. After 60 days, [latex]A(60)\\approx 0.3[\/latex] grams.<\/p>\n<p>33.\u00a0[latex]f\\left(t\\right)=250{e}^{\\left(-0.00914t\\right)}[\/latex]; half-life: about [latex]\\text{76}[\/latex] minutes<\/p>\n<p>35.\u00a0[latex]r\\approx -0.0667[\/latex], So the hourly decay rate is about 6.67%<\/p>\n<p>37.\u00a0[latex]f\\left(t\\right)=1350{e}^{\\left(0.03466t\\right)}[\/latex]; after 3 hours: [latex]P\\left(180\\right)\\approx 691,200[\/latex]<\/p>\n<p>40.\u00a0 [latex]T(t)=69+31e^{\\left(\\frac{1}{15}\\ln\\left(\\frac{26}{31}\\right)\\right)t}[\/latex].<\/p>\n<p>41.\u00a0about 88 minutes<\/p>\n<h2>Fitting Exponential Models to Data<\/h2>\n<p>4. A scatterplot that is best described by a logarithmic model would show a rapid increase or decrease at first, followed by a gradual leveling off as the input values increase. The data points would form a curve that rises (or falls) quickly and then flattens.<\/p>\n<p>6. E<\/p>\n<p>7. C<\/p>\n<p>8. A<\/p>\n<p>9. B<\/p>\n<p>10. D<\/p>\n<p>11.\u00a0[latex]P\\left(0\\right)=22[\/latex] ; 175<\/p>\n<p>13.\u00a0[latex]p\\approx 2.67[\/latex]<\/p>\n<p>16. <img loading=\"lazy\" decoding=\"async\" class=\"alignnone  wp-image-315\" src=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM.png\" alt=\"The graph is a logistic growth function. It increases slowly at first, then more rapidly, and finally levels off around 27 months near the max capacity of 68.    For small x-values near 0, the y-values are close to 0. Around x equals 6, the y-value is about 15. Around x equals 12, the y-value is about 45. Around x equals 18, the y-value is about 60.\" width=\"249\" height=\"204\" srcset=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM.png 1296w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM-300x246.png 300w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM-1024x839.png 1024w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM-768x629.png 768w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM-65x53.png 65w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM-225x184.png 225w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02180626\/Screenshot-2026-02-02-at-11.02.27%E2%80%AFAM-350x287.png 350w\" sizes=\"(max-width: 249px) 100vw, 249px\" \/><\/p>\n<p>17. 4 koi<\/p>\n<p>18. 6.8 months<\/p>\n<p>20. <img loading=\"lazy\" decoding=\"async\" class=\"alignnone  wp-image-316\" src=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM.png\" alt=\"The graph is a logistic growth function. It increases slowly at first, then more rapidly, and then levels off as x increases.    The graph has approximate values:  At x equals 0, y is close to 0.  At x equals 5, y is about 80.  At x equals 10, y is about 400.  At x equals 15, y is about 550.  At x equals 20, y is about 580.    The graph approaches a horizontal asymptote at y equals 588 but does not reach it.\" width=\"252\" height=\"191\" srcset=\"https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM.png 1414w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM-300x227.png 300w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM-1024x776.png 1024w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM-768x582.png 768w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM-65x49.png 65w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM-225x171.png 225w, https:\/\/content-cdn.one.lumenlearning.com\/wp-content\/uploads\/sites\/60\/2026\/02\/02181125\/Screenshot-2026-02-02-at-11.10.22%E2%80%AFAM-350x265.png 350w\" sizes=\"(max-width: 252px) 100vw, 252px\" \/><\/p>\n<p>21. 10 wolves<\/p>\n<p>23.\u00a0about 5.4 years.<\/p>\n<p>25.<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010839\/CNX_PreCalc_Figure_04_08_2102.jpg\" alt=\"Graph of the table\u2019s values.\" \/><\/p>\n<p>26. [latex]f(x)\\approx 795(1.415)^x[\/latex]<span id=\"fs-id1436308\"><\/span><\/p>\n<p>31.\u00a0[latex]f\\left(x\\right)=731.92{\\left(0.738\\right)}^{x}[\/latex]<\/p>\n<p>35.<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010839\/CNX_PreCalc_Figure_04_08_2162.jpg\" alt=\"Graph of the table\u2019s values.\" \/><\/p>\n<p>36. [latex]y\\approx 5.06+1.93\\ln(x)[\/latex]<\/p>\n<p>37.\u00a0[latex]f\\left(10\\right)\\approx 9.5[\/latex]<\/p>\n<p>40. <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010840\/CNX_PreCalc_Figure_04_08_2202.jpg\" alt=\"Graph of a scattered plot with an estimation line.\" \/><\/p>\n<p>41.\u00a0[latex]f\\left(x\\right)=7.544 - 2.268\\mathrm{ln}\\left(x\\right)[\/latex]<\/p>\n<p>45.<br \/>\n<img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010840\/CNX_PreCalc_Figure_04_08_2222.jpg\" alt=\"Graph of the table\u2019s values.\" \/><\/p>\n<p>46. [latex]y\\approx 26.91-24.20e^{-0.264x}[\/latex]<\/p>\n<p>51.\u00a0[latex]f\\left(x\\right)=\\frac{136.068}{1+10.324{e}^{-0.480x}}[\/latex]<\/p>\n<p>53.\u00a0about 136<\/p>\n","protected":false},"author":13,"menu_order":8,"template":"","meta":{"_candela_citation":"[]","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"part":224,"module-header":"- Select Header -","content_attributions":[],"internal_book_links":[],"video_content":null,"cc_video_embed_content":{"cc_scripts":"","media_targets":[]},"try_it_collection":null,"_links":{"self":[{"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/chapters\/312"}],"collection":[{"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/wp\/v2\/users\/13"}],"version-history":[{"count":3,"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/chapters\/312\/revisions"}],"predecessor-version":[{"id":317,"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/chapters\/312\/revisions\/317"}],"part":[{"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/parts\/224"}],"metadata":[{"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/chapters\/312\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/wp\/v2\/media?parent=312"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/pressbooks\/v2\/chapter-type?post=312"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/wp\/v2\/contributor?post=312"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/qrpracticepages\/wp-json\/wp\/v2\/license?post=312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}