{"id":15537,"date":"2019-09-04T20:50:33","date_gmt":"2019-09-04T20:50:33","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/precalculus\/?post_type=chapter&#038;p=15537"},"modified":"2025-02-05T05:19:19","modified_gmt":"2025-02-05T05:19:19","slug":"problem-set-12-complex-numbers","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/precalculus\/chapter\/problem-set-12-complex-numbers\/","title":{"raw":"Problem Set 12: Complex Numbers","rendered":"Problem Set 12: Complex Numbers"},"content":{"raw":"1. Explain how to add complex numbers.\r\n\r\n2.\u00a0What is the basic principle in multiplication of complex numbers?\r\n\r\n3. Give an example to show the product of two imaginary numbers is not always imaginary.\r\n\r\n4.\u00a0What is a characteristic of the plot of a real number in the complex plane?\r\n\r\nFor the following exercises, evaluate the algebraic expressions.\r\n\r\n5. [latex]\\text{If }f\\left(x\\right)={x}^{2}+x - 4[\/latex], evaluate [latex]f\\left(2i\\right)[\/latex].\r\n\r\n6.\u00a0[latex]\\text{If }f\\left(x\\right)={x}^{3}-2[\/latex], evaluate [latex]f\\left(i\\right)[\/latex].\r\n\r\n7. [latex]\\text{If }f\\left(x\\right)={x}^{2}+3x+5[\/latex], evaluate [latex]f\\left(2+i\\right)[\/latex].\r\n\r\n8.\u00a0[latex]\\text{If }f\\left(x\\right)=2{x}^{2}+x - 3[\/latex], evaluate [latex]f\\left(2 - 3i\\right)[\/latex].\r\n\r\n9. [latex]\\text{If }f\\left(x\\right)=\\frac{x+1}{2-x}[\/latex], evaluate [latex]f\\left(5i\\right)[\/latex].\r\n\r\n10.\u00a0[latex]\\text{If }f\\left(x\\right)=\\frac{1+2x}{x+3}[\/latex], evaluate [latex]f\\left(4i\\right)[\/latex].\r\n\r\nFor the following exercises, determine the number of real and nonreal solutions for each quadratic function shown.\r\n\r\n11.\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010710\/CNX_Precalc_Figure_03_01_2012.jpg\" alt=\"Graph of a parabola intersecting the real axis.\" \/>\r\n\r\n12.\r\n<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/1227\/2015\/04\/03010710\/CNX_Precalc_Figure_03_01_2022.jpg\" alt=\"Graph of a parabola not intersecting the real axis.\" \/>\r\nFor the following exercises, plot the complex numbers on the complex plane.\r\n\r\n13. [latex]1 - 2i[\/latex]\r\n\r\n14. [latex]-2+3i[\/latex]\r\n\r\n15.\u00a0<em>i<\/em>\r\n\r\n16. [latex]-3 - 4i[\/latex]\r\n\r\nFor the following exercises, perform the indicated operation and express the result as a simplified complex number.\r\n\r\n17. [latex]\\left(3+2i\\right)+\\left(5 - 3i\\right)[\/latex]\r\n\r\n18.\u00a0[latex]\\left(-2 - 4i\\right)+\\left(1+6i\\right)[\/latex]\r\n\r\n19. [latex]\\left(-5+3i\\right)-\\left(6-i\\right)[\/latex]\r\n\r\n20.\u00a0[latex]\\left(2 - 3i\\right)-\\left(3+2i\\right)[\/latex]\r\n\r\n21. [latex]\\left(-4+4i\\right)-\\left(-6+9i\\right)[\/latex]\r\n\r\n22.\u00a0[latex]\\left(2+3i\\right)\\left(4i\\right)[\/latex]\r\n\r\n23. [latex]\\left(5 - 2i\\right)\\left(3i\\right)[\/latex]\r\n\r\n24.\u00a0[latex]\\left(6 - 2i\\right)\\left(5\\right)[\/latex]\r\n\r\n25. [latex]\\left(-2+4i\\right)\\left(8\\right)[\/latex]\r\n\r\n26.\u00a0[latex]\\left(2+3i\\right)\\left(4-i\\right)[\/latex]\r\n\r\n27. [latex]\\left(-1+2i\\right)\\left(-2+3i\\right)[\/latex]\r\n\r\n28.\u00a0[latex]\\left(4 - 2i\\right)\\left(4+2i\\right)[\/latex]\r\n\r\n29. [latex]\\left(3+4i\\right)\\left(3 - 4i\\right)[\/latex]\r\n\r\n30.\u00a0[latex]\\frac{3+4i}{2}[\/latex]\r\n\r\n31. [latex]\\frac{6 - 2i}{3}[\/latex]\r\n\r\n32.\u00a0[latex]\\frac{-5+3i}{2i}[\/latex]\r\n\r\n33. [latex]\\frac{6+4i}{i}[\/latex]\r\n\r\n34.\u00a0[latex]\\frac{2 - 3i}{4+3i}[\/latex]\r\n\r\n35. [latex]\\frac{3+4i}{2-i}[\/latex]\r\n\r\n36.\u00a0[latex]\\frac{2+3i}{2 - 3i}[\/latex]\r\n\r\n37. [latex]\\sqrt{-9}+3\\sqrt{-16}[\/latex]\r\n\r\n38.\u00a0[latex]-\\sqrt{-4}-4\\sqrt{-25}[\/latex]\r\n\r\n39. [latex]\\frac{2+\\sqrt{-12}}{2}[\/latex]\r\n\r\n40.\u00a0[latex]\\frac{4+\\sqrt{-20}}{2}[\/latex]\r\n\r\n41. [latex]{i}^{8}[\/latex]\r\n\r\n42.\u00a0[latex]{i}^{15}[\/latex]\r\n\r\n43. [latex]{i}^{22}[\/latex]\r\n\r\nFor the following exercises, use a calculator to help answer the questions.\r\n\r\n44. Evaluate [latex]{\\left(1+i\\right)}^{k}[\/latex] for [latex]k=\\text{4, 8, and 12}\\text{.}[\/latex] Predict the value if [latex]k=16[\/latex].\r\n\r\n45. Evaluate [latex]{\\left(1-i\\right)}^{k}[\/latex] for [latex]k=\\text{2, 6, and 10}\\text{.}[\/latex] Predict the value if [latex]k=14[\/latex].\r\n\r\n46.\u00a0Evaluate [latex]\\left(1+i\\right)^{k}-\\left(1-i\\right)^{k}[\/latex] for [latex]k=\\text{4, 8, and 12}[\/latex]. Predict the value for [latex]k=16[\/latex].\r\n\r\n47. Show that a solution of [latex]{x}^{6}+1=0[\/latex] is [latex]\\frac{\\sqrt{3}}{2}+\\frac{1}{2}i[\/latex].\r\n\r\n48.\u00a0Show that a solution of [latex]{x}^{8}-1=0[\/latex] is [latex]\\frac{\\sqrt{2}}{2}+\\frac{\\sqrt{2}}{2}i[\/latex].\r\n\r\nFor the following exercises, evaluate the expressions, writing the result as a simplified complex number.\r\n\r\n49. [latex]\\frac{1}{i}+\\frac{4}{{i}^{3}}[\/latex]\r\n\r\n50.\u00a0[latex]\\frac{1}{{i}^{11}}-\\frac{1}{{i}^{21}}[\/latex]\r\n\r\n51. [latex]{i}^{7}\\left(1+{i}^{2}\\right)[\/latex]\r\n\r\n52.\u00a0[latex]{i}^{-3}+5{i}^{7}[\/latex]\r\n\r\n53. [latex]\\frac{\\left(2+i\\right)\\left(4 - 2i\\right)}{\\left(1+i\\right)}[\/latex]\r\n\r\n54.\u00a0[latex]\\frac{\\left(1+3i\\right)\\left(2 - 4i\\right)}{\\left(1+2i\\right)}[\/latex]\r\n\r\n55. [latex]\\frac{{\\left(3+i\\right)}^{2}}{{\\left(1+2i\\right)}^{2}}[\/latex]\r\n\r\n56.\u00a0[latex]\\frac{3+2i}{2+i}+\\left(4+3i\\right)[\/latex]\r\n\r\n57. [latex]\\frac{4+i}{i}+\\frac{3 - 4i}{1-i}[\/latex]\r\n\r\n58.\u00a0[latex]\\frac{3+2i}{1+2i}-\\frac{2 - 3i}{3+i}[\/latex]","rendered":"<p>1. Explain how to add complex numbers.<\/p>\n<p>2.\u00a0What is the basic principle in multiplication of complex numbers?<\/p>\n<p>3. Give an example to show the product of two imaginary numbers is not always imaginary.<\/p>\n<p>4.\u00a0What is a characteristic of the plot of a real number in the complex plane?<\/p>\n<p>For the following exercises, evaluate the algebraic expressions.<\/p>\n<p>5. [latex]\\text{If }f\\left(x\\right)={x}^{2}+x - 4[\/latex], evaluate [latex]f\\left(2i\\right)[\/latex].<\/p>\n<p>6.\u00a0[latex]\\text{If }f\\left(x\\right)={x}^{3}-2[\/latex], evaluate [latex]f\\left(i\\right)[\/latex].<\/p>\n<p>7. [latex]\\text{If }f\\left(x\\right)={x}^{2}+3x+5[\/latex], evaluate [latex]f\\left(2+i\\right)[\/latex].<\/p>\n<p>8.\u00a0[latex]\\text{If }f\\left(x\\right)=2{x}^{2}+x - 3[\/latex], evaluate [latex]f\\left(2 - 3i\\right)[\/latex].<\/p>\n<p>9. [latex]\\text{If }f\\left(x\\right)=\\frac{x+1}{2-x}[\/latex], evaluate [latex]f\\left(5i\\right)[\/latex].<\/p>\n<p>10.\u00a0[latex]\\text{If }f\\left(x\\right)=\\frac{1+2x}{x+3}[\/latex], evaluate [latex]f\\left(4i\\right)[\/latex].<\/p>\n<p>For the following exercises, determine the number of real and nonreal solutions for each quadratic function shown.<\/p>\n<p>11.<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\/03010710\/CNX_Precalc_Figure_03_01_2012.jpg\" alt=\"Graph of a parabola intersecting the real axis.\" \/><\/p>\n<p>12.<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\/03010710\/CNX_Precalc_Figure_03_01_2022.jpg\" alt=\"Graph of a parabola not intersecting the real axis.\" \/><br \/>\nFor the following exercises, plot the complex numbers on the complex plane.<\/p>\n<p>13. [latex]1 - 2i[\/latex]<\/p>\n<p>14. [latex]-2+3i[\/latex]<\/p>\n<p>15.\u00a0<em>i<\/em><\/p>\n<p>16. [latex]-3 - 4i[\/latex]<\/p>\n<p>For the following exercises, perform the indicated operation and express the result as a simplified complex number.<\/p>\n<p>17. [latex]\\left(3+2i\\right)+\\left(5 - 3i\\right)[\/latex]<\/p>\n<p>18.\u00a0[latex]\\left(-2 - 4i\\right)+\\left(1+6i\\right)[\/latex]<\/p>\n<p>19. [latex]\\left(-5+3i\\right)-\\left(6-i\\right)[\/latex]<\/p>\n<p>20.\u00a0[latex]\\left(2 - 3i\\right)-\\left(3+2i\\right)[\/latex]<\/p>\n<p>21. [latex]\\left(-4+4i\\right)-\\left(-6+9i\\right)[\/latex]<\/p>\n<p>22.\u00a0[latex]\\left(2+3i\\right)\\left(4i\\right)[\/latex]<\/p>\n<p>23. [latex]\\left(5 - 2i\\right)\\left(3i\\right)[\/latex]<\/p>\n<p>24.\u00a0[latex]\\left(6 - 2i\\right)\\left(5\\right)[\/latex]<\/p>\n<p>25. [latex]\\left(-2+4i\\right)\\left(8\\right)[\/latex]<\/p>\n<p>26.\u00a0[latex]\\left(2+3i\\right)\\left(4-i\\right)[\/latex]<\/p>\n<p>27. [latex]\\left(-1+2i\\right)\\left(-2+3i\\right)[\/latex]<\/p>\n<p>28.\u00a0[latex]\\left(4 - 2i\\right)\\left(4+2i\\right)[\/latex]<\/p>\n<p>29. [latex]\\left(3+4i\\right)\\left(3 - 4i\\right)[\/latex]<\/p>\n<p>30.\u00a0[latex]\\frac{3+4i}{2}[\/latex]<\/p>\n<p>31. [latex]\\frac{6 - 2i}{3}[\/latex]<\/p>\n<p>32.\u00a0[latex]\\frac{-5+3i}{2i}[\/latex]<\/p>\n<p>33. [latex]\\frac{6+4i}{i}[\/latex]<\/p>\n<p>34.\u00a0[latex]\\frac{2 - 3i}{4+3i}[\/latex]<\/p>\n<p>35. [latex]\\frac{3+4i}{2-i}[\/latex]<\/p>\n<p>36.\u00a0[latex]\\frac{2+3i}{2 - 3i}[\/latex]<\/p>\n<p>37. [latex]\\sqrt{-9}+3\\sqrt{-16}[\/latex]<\/p>\n<p>38.\u00a0[latex]-\\sqrt{-4}-4\\sqrt{-25}[\/latex]<\/p>\n<p>39. [latex]\\frac{2+\\sqrt{-12}}{2}[\/latex]<\/p>\n<p>40.\u00a0[latex]\\frac{4+\\sqrt{-20}}{2}[\/latex]<\/p>\n<p>41. [latex]{i}^{8}[\/latex]<\/p>\n<p>42.\u00a0[latex]{i}^{15}[\/latex]<\/p>\n<p>43. [latex]{i}^{22}[\/latex]<\/p>\n<p>For the following exercises, use a calculator to help answer the questions.<\/p>\n<p>44. Evaluate [latex]{\\left(1+i\\right)}^{k}[\/latex] for [latex]k=\\text{4, 8, and 12}\\text{.}[\/latex] Predict the value if [latex]k=16[\/latex].<\/p>\n<p>45. Evaluate [latex]{\\left(1-i\\right)}^{k}[\/latex] for [latex]k=\\text{2, 6, and 10}\\text{.}[\/latex] Predict the value if [latex]k=14[\/latex].<\/p>\n<p>46.\u00a0Evaluate [latex]\\left(1+i\\right)^{k}-\\left(1-i\\right)^{k}[\/latex] for [latex]k=\\text{4, 8, and 12}[\/latex]. Predict the value for [latex]k=16[\/latex].<\/p>\n<p>47. Show that a solution of [latex]{x}^{6}+1=0[\/latex] is [latex]\\frac{\\sqrt{3}}{2}+\\frac{1}{2}i[\/latex].<\/p>\n<p>48.\u00a0Show that a solution of [latex]{x}^{8}-1=0[\/latex] is [latex]\\frac{\\sqrt{2}}{2}+\\frac{\\sqrt{2}}{2}i[\/latex].<\/p>\n<p>For the following exercises, evaluate the expressions, writing the result as a simplified complex number.<\/p>\n<p>49. [latex]\\frac{1}{i}+\\frac{4}{{i}^{3}}[\/latex]<\/p>\n<p>50.\u00a0[latex]\\frac{1}{{i}^{11}}-\\frac{1}{{i}^{21}}[\/latex]<\/p>\n<p>51. [latex]{i}^{7}\\left(1+{i}^{2}\\right)[\/latex]<\/p>\n<p>52.\u00a0[latex]{i}^{-3}+5{i}^{7}[\/latex]<\/p>\n<p>53. [latex]\\frac{\\left(2+i\\right)\\left(4 - 2i\\right)}{\\left(1+i\\right)}[\/latex]<\/p>\n<p>54.\u00a0[latex]\\frac{\\left(1+3i\\right)\\left(2 - 4i\\right)}{\\left(1+2i\\right)}[\/latex]<\/p>\n<p>55. [latex]\\frac{{\\left(3+i\\right)}^{2}}{{\\left(1+2i\\right)}^{2}}[\/latex]<\/p>\n<p>56.\u00a0[latex]\\frac{3+2i}{2+i}+\\left(4+3i\\right)[\/latex]<\/p>\n<p>57. [latex]\\frac{4+i}{i}+\\frac{3 - 4i}{1-i}[\/latex]<\/p>\n<p>58.\u00a0[latex]\\frac{3+2i}{1+2i}-\\frac{2 - 3i}{3+i}[\/latex]<\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-15537\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Precalculus. <strong>Authored by<\/strong>: Jay Abramson, et al.. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175.\">http:\/\/cnx.org\/contents\/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175.<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at: http:\/\/cnx.org\/contents\/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175.<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":169554,"menu_order":10,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Precalculus\",\"author\":\"Jay Abramson, et al.\",\"organization\":\"OpenStax\",\"url\":\"http:\/\/cnx.org\/contents\/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175.\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at: http:\/\/cnx.org\/contents\/fd53eae1-fa23-47c7-bb1b-972349835c3c@5.175.\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-15537","chapter","type-chapter","status-publish","hentry"],"part":10733,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/15537","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/users\/169554"}],"version-history":[{"count":1,"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/15537\/revisions"}],"predecessor-version":[{"id":15539,"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/15537\/revisions\/15539"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/parts\/10733"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapters\/15537\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/media?parent=15537"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/pressbooks\/v2\/chapter-type?post=15537"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/contributor?post=15537"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/precalculus\/wp-json\/wp\/v2\/license?post=15537"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}