{"id":1266,"date":"2015-11-12T18:35:30","date_gmt":"2015-11-12T18:35:30","guid":{"rendered":"https:\/\/courses.candelalearning.com\/collegealgebra1xmaster\/?post_type=chapter&#038;p=1266"},"modified":"2017-03-19T07:33:27","modified_gmt":"2017-03-19T07:33:27","slug":"describe-local-behavior-of-polynomial-functions","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/chapter\/describe-local-behavior-of-polynomial-functions\/","title":{"raw":"Describe local behavior of polynomial functions","rendered":"Describe local behavior of polynomial functions"},"content":{"raw":"<section id=\"fs-id1165137735781\">\r\n<h2>Identifying Local Behavior of Polynomial Functions<\/h2>\r\n<p id=\"fs-id1165134054039\">In addition to the end behavior of polynomial functions, we are also interested in what happens in the \"middle\" of the function. In particular, we are interested in locations where graph behavior changes. A <strong>turning point <\/strong>is a point at which the function values change from increasing to decreasing or decreasing to increasing.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"731\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201343\/CNX_Precalc_Figure_03_03_0172.jpg\" alt=\"\" width=\"731\" height=\"629\" \/> <b>Figure 10<\/b>[\/caption]\r\n<p id=\"fs-id1165137417044\">We are also interested in the intercepts. As with all functions, the <em>y-<\/em>intercept is the point at which the graph intersects the vertical axis. The point corresponds to the coordinate pair in which the input value is zero. Because a polynomial is a function, only one output value corresponds to each input value so there can be only one <em>y-<\/em>intercept [latex]\\left(0,{a}_{0}\\right).[\/latex] The <em>x-<\/em>intercepts occur at the input values that correspond to an output value of zero. It is possible to have more than one <em>x-<\/em>intercept.\u00a0<span id=\"fs-id1165135511323\">\r\n<\/span><\/p>\r\n\r\n<div id=\"fs-id1165135378843\" class=\"note textbox\">\r\n<h3 class=\"title\">A General Note: Intercepts and Turning Points of Polynomial Functions<\/h3>\r\n<p id=\"fs-id1165137638552\">A <strong>turning point<\/strong> of a graph is a point at which the graph changes direction from increasing to decreasing or decreasing to increasing. The <em>y-<\/em>intercept is the point at which the function has an input value of zero. The <em>x<\/em>-intercepts are the points at which the output value is zero.<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-id1165137766902\" class=\"note precalculus howto textbox\">\r\n<h3 id=\"fs-id1165137645233\">How To: Given a polynomial function, determine the intercepts.<\/h3>\r\n<ol id=\"fs-id1165137571388\">\r\n \t<li>Determine the <em>y-<\/em>intercept by setting [latex]x=0[\/latex] and finding the corresponding output value.<\/li>\r\n \t<li>Determine the <em>x<\/em>-intercepts by solving for the input values that yield an output value of zero.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<div id=\"Example_03_03_08\" class=\"example\">\r\n<div id=\"fs-id1165137435581\" class=\"exercise\">\r\n<div id=\"fs-id1165137803210\" class=\"problem textbox shaded\">\r\n<h3>Example 8: Determining the Intercepts of a Polynomial Function<\/h3>\r\n<p id=\"fs-id1165137441767\">Given the polynomial function [latex]f\\left(x\\right)=\\left(x - 2\\right)\\left(x+1\\right)\\left(x - 4\\right),\\\\[\/latex] written in factored form for your convenience, determine the <em>y<\/em>- and\u00a0<em>x<\/em>-intercepts.<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-id1165135251466\" class=\"solution textbox shaded\">\r\n<h3>Solution<\/h3>\r\n<p id=\"fs-id1165135251468\">The <em>y-<\/em>intercept occurs when the input is zero so substitute 0 for <em>x<\/em>.<\/p>\r\n\r\n<div id=\"eip-id1165133032876\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}f\\left(0\\right)=\\left(0 - 2\\right)\\left(0+1\\right)\\left(0 - 4\\right)\\hfill \\\\ \\text{ }=\\left(-2\\right)\\left(1\\right)\\left(-4\\right)\\hfill \\\\ \\text{ }=8\\hfill \\end{cases}\\\\[\/latex]<\/div>\r\n<p id=\"fs-id1165135689436\">The <em>y-<\/em>intercept is (0, 8).<\/p>\r\n<p id=\"fs-id1165137863224\">The <em>x<\/em>-intercepts occur when the output is zero.<\/p>\r\n\r\n<div id=\"eip-id1165134380311\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}\\text{ }0=\\left(x - 2\\right)\\left(x+1\\right)\\left(x - 4\\right)\\hfill \\\\ x - 2=0\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; x+1=0\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; x - 4=0\\hfill \\\\ \\text{ }x=2\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; \\text{ }x=-1\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; x=4 \\end{cases}[\/latex]<\/div>\r\n<p id=\"fs-id1165135316178\">The\u00a0<i>x<\/i>-intercepts are<\/p>\r\n[latex]\\left(2,0\\right),\\left(-1,0\\right), \\text{and} \\left(4,0\\right).\\\\[\/latex]\r\n\r\nWe can see these intercepts on the graph of the function shown in Figure 11.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201345\/CNX_Precalc_Figure_03_03_0182.jpg\" alt=\"Graph of f(x)=(x-2)(x+1)(x-4), which labels all the intercepts.\" width=\"487\" height=\"630\" \/> <b>Figure 11<\/b>[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div id=\"Example_03_03_09\" class=\"example\">\r\n<div id=\"fs-id1165137834894\" class=\"exercise\">\r\n<div id=\"fs-id1165137834896\" class=\"problem textbox shaded\">\r\n<h3>Example 9: Determining the Intercepts of a Polynomial Function with Factoring<\/h3>\r\n<p id=\"fs-id1165137628033\">Given the polynomial function [latex]f\\left(x\\right)={x}^{4}-4{x}^{2}-45,\\\\[\/latex] determine the <em>y<\/em>- and\u00a0<em>x<\/em>-intercepts.<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-id1165137634473\" class=\"solution textbox shaded\">\r\n<h3>Solution<\/h3>\r\nThe <em>y-<\/em>intercept occurs when the input is zero.\r\n<div id=\"eip-id1165132943488\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases} \\\\ f\\left(0\\right)={\\left(0\\right)}^{4}-4{\\left(0\\right)}^{2}-45\\hfill \\hfill \\\\ \\text{ }=-45\\hfill \\end{cases}\\\\[\/latex]<\/div>\r\n<p id=\"fs-id1165135653967\">The <em>y-<\/em>intercept is [latex]\\left(0,-45\\right).[\/latex]<\/p>\r\n<p id=\"fs-id1165135152099\">The <em>x<\/em>-intercepts occur when the output is zero. To determine when the output is zero, we will need to factor the polynomial.<\/p>\r\n\r\n<div id=\"eip-id1165135376171\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}f\\left(x\\right)={x}^{4}-4{x}^{2}-45\\hfill \\\\ =\\left({x}^{2}-9\\right)\\left({x}^{2}+5\\right)\\hfill \\\\ =\\left(x - 3\\right)\\left(x+3\\right)\\left({x}^{2}+5\\right)\\hfill \\end{cases}[\/latex]<\/div>\r\n<div class=\"equation unnumbered\"><\/div>\r\n<div class=\"equation unnumbered\" style=\"text-align: center\"><\/div>\r\n<div id=\"eip-id1165135684199\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]0=\\left(x - 3\\right)\\left(x+3\\right)\\left({x}^{2}+5\\right)\\\\[\/latex]<\/div>\r\n<div class=\"equation unnumbered\" style=\"text-align: center\"><\/div>\r\n<div id=\"eip-id1165134383791\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}x - 3=0\\hfill &amp; \\text{or}\\hfill &amp; x+3=0\\hfill &amp; \\text{or}\\hfill &amp; {x}^{2}+5=0\\hfill \\\\ \\text{ }x=3\\hfill &amp; \\text{or}\\hfill &amp; \\text{ }x=-3\\hfill &amp; \\text{or}\\hfill &amp; \\text{(no real solution)}\\hfill \\end{cases}\\\\[\/latex]<\/div>\r\n<p id=\"fs-id1165135436471\">The <em>x<\/em>-intercepts are [latex]\\left(3,0\\right) \\text{and} \\left(-3,0\\right).[\/latex]<\/p>\r\nWe can see these intercepts on the graph of the function shown in Figure 12. We can see that the function is even because [latex]f\\left(x\\right)=f\\left(-x\\right).\\\\[\/latex]\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201346\/CNX_Precalc_Figure_03_03_0192.jpg\" alt=\"Graph of f(x)=x^4-4x^2-45, which labels all the intercepts at (-3, 0), (3, 0), and (0, -45).\" width=\"487\" height=\"426\" \/> <b>Figure 12<\/b>[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"bcc-box bcc-success\">\r\n<h3>Try It 6<\/h3>\r\n<p id=\"fs-id1165137405244\">Given the polynomial function [latex]f\\left(x\\right)=2{x}^{3}-6{x}^{2}-20x,\\\\[\/latex] determine the <em>y<\/em>- and<em> x<\/em>-intercepts.<\/p>\r\n<a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a>\r\n\r\n<\/div>\r\n<\/section><section id=\"fs-id1165134080932\">\r\n<h2>Comparing Smooth and Continuous Graphs<\/h2>\r\n<p id=\"fs-id1165137692509\">The degree of a polynomial function helps us to determine the number of <em>x<\/em>-intercepts and the number of turning points. A polynomial function of\u00a0<em>n<\/em>th degree is the product of <em>n<\/em>\u00a0factors, so it will have at most <em>n<\/em>\u00a0roots or zeros, or <em>x<\/em>-intercepts. The graph of the polynomial function of degree <em>n<\/em>\u00a0must have at most <em>n<\/em> \u2013 1\u00a0turning points. This means the graph has at most one fewer turning point than the degree of the polynomial or one fewer than the number of factors.<\/p>\r\n<p id=\"fs-id1165137657937\">A <strong>continuous function<\/strong> has no breaks in its graph: the graph can be drawn without lifting the pen from the paper. A <strong>smooth curve<\/strong> is a graph that has no sharp corners. The turning points of a smooth graph must always occur at rounded curves. The graphs of polynomial functions are both continuous and smooth.<\/p>\r\n\r\n<div id=\"fs-id1165137847104\" class=\"note textbox\">\r\n<h3 class=\"title\">A General Note: Intercepts and Turning Points of Polynomials<\/h3>\r\n<p id=\"fs-id1165137405499\">A polynomial of degree <em>n<\/em>\u00a0will have, at most, <em>n<\/em>\u00a0<em>x<\/em>-intercepts and <em>n<\/em> \u2013 1\u00a0turning points.<\/p>\r\n\r\n<\/div>\r\n<div id=\"Example_03_03_10\" class=\"example\">\r\n<div id=\"fs-id1165135237034\" class=\"exercise\">\r\n<div id=\"fs-id1165135237036\" class=\"problem textbox shaded\">\r\n<h3>Example 10: Determining the Number of Intercepts and Turning Points of a Polynomial<\/h3>\r\n<p id=\"fs-id1165134152759\">Without graphing the function, determine the local behavior of the function by finding the maximum number of <em>x<\/em>-intercepts and turning points for [latex]f\\left(x\\right)=-3{x}^{10}+4{x}^{7}-{x}^{4}+2{x}^{3}.\\\\[\/latex]<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-id1165135414339\" class=\"solution textbox shaded\">\r\n<h3>Solution<\/h3>\r\n<p id=\"fs-id1165135414341\">The polynomial has a degree of 10, so there are at most <em>n<\/em>\u00a0<em>x<\/em>-intercepts and at most <em>n<\/em>\u00a0\u2013 1 turning points.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"bcc-box bcc-success\">\r\n<h3>Try It 7<\/h3>\r\nWithout graphing the function, determine the maximum number of <em>x<\/em>-intercepts and turning points for [latex]f\\left(x\\right)=108 - 13{x}^{9}-8{x}^{4}+14{x}^{12}+2{x}^{3}\\\\[\/latex]\r\n\r\n<a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a>\r\n\r\n<\/div>\r\n<div id=\"Example_03_03_11\" class=\"example\">\r\n<div class=\"exercise\">\r\n<div id=\"fs-id1165137435066\" class=\"problem textbox shaded\">\r\n<h3>Example 11: Drawing Conclusions about a Polynomial Function from the Graph<\/h3>\r\nWhat can we conclude about the polynomial represented by the graph shown in the graph in Figure 13\u00a0based on its intercepts and turning points?\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201347\/CNX_Precalc_Figure_03_03_0202.jpg\" alt=\"Graph of an even-degree polynomial.\" width=\"487\" height=\"367\" \/> <b>Figure 13<\/b>[\/caption]\r\n\r\n<\/div>\r\n<div id=\"fs-id1165137737264\" class=\"solution textbox shaded\">\r\n<h3>Solution<\/h3>\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201349\/CNX_Precalc_Figure_03_03_0212.jpg\" alt=\"Graph of an even-degree polynomial that denotes the turning points and intercepts.\" width=\"487\" height=\"368\" \/> <b>Figure 14<\/b>[\/caption]\r\n<p id=\"fs-id1165131926327\">The end behavior of the graph tells us this is the graph of an even-degree polynomial.\u00a0<span id=\"fs-id1165137883772\">\r\n<\/span><\/p>\r\n<p id=\"fs-id1165135670389\">The graph has 2 <em>x<\/em>-intercepts, suggesting a degree of 2 or greater, and 3 turning points, suggesting a degree of 4 or greater. Based on this, it would be reasonable to conclude that the degree is even and at least 4.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"bcc-box bcc-success\">\r\n<h3>Try It 8<\/h3>\r\nWhat can we conclude about the polynomial represented by Figure 15\u00a0based on its intercepts and turning points?\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201350\/CNX_Precalc_Figure_03_03_0224.jpg\" alt=\"Graph of an odd-degree polynomial.\" width=\"487\" height=\"442\" \/> <b>Figure 15<\/b>[\/caption]\r\n\r\n<a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a>\r\n\r\n<\/div>\r\n<div id=\"Example_03_03_12\" class=\"example\">\r\n<div id=\"fs-id1165135184013\" class=\"exercise\">\r\n<div id=\"fs-id1165137725458\" class=\"problem textbox shaded\">\r\n<h3>Example 12: Drawing Conclusions about a Polynomial Function from the Factors<\/h3>\r\n<p id=\"fs-id1165135435639\">Given the function [latex]f\\left(x\\right)=-4x\\left(x+3\\right)\\left(x - 4\\right),\\\\[\/latex]\u00a0determine the local behavior.<\/p>\r\n\r\n<\/div>\r\n<div id=\"fs-id1165135457721\" class=\"solution textbox shaded\">\r\n<h3>Solution<\/h3>\r\n<p id=\"fs-id1165135457723\">The <em>y<\/em>-intercept is found by evaluating [latex]f\\left(0\\right).[\/latex]<\/p>\r\n\r\n<div id=\"eip-id1165134587897\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}f\\left(0\\right)=-4\\left(0\\right)\\left(0+3\\right)\\left(0 - 4\\right)\\hfill \\hfill \\\\ \\text{ }=0\\hfill \\end{cases}\\\\[\/latex]<\/div>\r\n<p id=\"fs-id1165135245749\">The <em>y<\/em>-intercept is [latex]\\left(0,0\\right).[\/latex]<\/p>\r\n<p id=\"fs-id1165135203755\">The <em>x<\/em>-intercepts are found by determining the zeros of the function.<\/p>\r\n\r\n<div id=\"eip-id1165135401630\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}0=-4x\\left(x+3\\right)\\left(x - 4\\right)\\\\ x=0\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; x+3=0\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; x - 4=0\\hfill \\\\ x=0\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; \\text{ }x=-3\\hfill &amp; \\hfill &amp; \\text{or}\\hfill &amp; \\hfill &amp; \\text{ }x=4\\end{cases}\\\\[\/latex]<\/div>\r\n<p id=\"fs-id1165135431016\">The <em>x<\/em>-intercepts are [latex]\\left(0,0\\right),\\left(-3,0\\right) \\text{and} \\left(4,0\\right).[\/latex]<\/p>\r\n<p id=\"fs-id1165137472984\">The degree is 3 so the graph has at most 2 turning points.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"bcc-box bcc-success\">\r\n<h3>Try It 9<\/h3>\r\n<p id=\"fs-id1165137575431\">Given the function [latex]f\\left(x\\right)=0.2\\left(x - 2\\right)\\left(x+1\\right)\\left(x - 5\\right),\\\\[\/latex] determine the local behavior.<\/p>\r\n<a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a>\r\n\r\n<\/div>\r\n<\/section>","rendered":"<section id=\"fs-id1165137735781\">\n<h2>Identifying Local Behavior of Polynomial Functions<\/h2>\n<p id=\"fs-id1165134054039\">In addition to the end behavior of polynomial functions, we are also interested in what happens in the &#8220;middle&#8221; of the function. In particular, we are interested in locations where graph behavior changes. A <strong>turning point <\/strong>is a point at which the function values change from increasing to decreasing or decreasing to increasing.<\/p>\n<div style=\"width: 741px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201343\/CNX_Precalc_Figure_03_03_0172.jpg\" alt=\"\" width=\"731\" height=\"629\" \/><\/p>\n<p class=\"wp-caption-text\"><b>Figure 10<\/b><\/p>\n<\/div>\n<p id=\"fs-id1165137417044\">We are also interested in the intercepts. As with all functions, the <em>y-<\/em>intercept is the point at which the graph intersects the vertical axis. The point corresponds to the coordinate pair in which the input value is zero. Because a polynomial is a function, only one output value corresponds to each input value so there can be only one <em>y-<\/em>intercept [latex]\\left(0,{a}_{0}\\right).[\/latex] The <em>x-<\/em>intercepts occur at the input values that correspond to an output value of zero. It is possible to have more than one <em>x-<\/em>intercept.\u00a0<span id=\"fs-id1165135511323\"><br \/>\n<\/span><\/p>\n<div id=\"fs-id1165135378843\" class=\"note textbox\">\n<h3 class=\"title\">A General Note: Intercepts and Turning Points of Polynomial Functions<\/h3>\n<p id=\"fs-id1165137638552\">A <strong>turning point<\/strong> of a graph is a point at which the graph changes direction from increasing to decreasing or decreasing to increasing. The <em>y-<\/em>intercept is the point at which the function has an input value of zero. The <em>x<\/em>-intercepts are the points at which the output value is zero.<\/p>\n<\/div>\n<div id=\"fs-id1165137766902\" class=\"note precalculus howto textbox\">\n<h3 id=\"fs-id1165137645233\">How To: Given a polynomial function, determine the intercepts.<\/h3>\n<ol id=\"fs-id1165137571388\">\n<li>Determine the <em>y-<\/em>intercept by setting [latex]x=0[\/latex] and finding the corresponding output value.<\/li>\n<li>Determine the <em>x<\/em>-intercepts by solving for the input values that yield an output value of zero.<\/li>\n<\/ol>\n<\/div>\n<div id=\"Example_03_03_08\" class=\"example\">\n<div id=\"fs-id1165137435581\" class=\"exercise\">\n<div id=\"fs-id1165137803210\" class=\"problem textbox shaded\">\n<h3>Example 8: Determining the Intercepts of a Polynomial Function<\/h3>\n<p id=\"fs-id1165137441767\">Given the polynomial function [latex]f\\left(x\\right)=\\left(x - 2\\right)\\left(x+1\\right)\\left(x - 4\\right),\\\\[\/latex] written in factored form for your convenience, determine the <em>y<\/em>&#8211; and\u00a0<em>x<\/em>-intercepts.<\/p>\n<\/div>\n<div id=\"fs-id1165135251466\" class=\"solution textbox shaded\">\n<h3>Solution<\/h3>\n<p id=\"fs-id1165135251468\">The <em>y-<\/em>intercept occurs when the input is zero so substitute 0 for <em>x<\/em>.<\/p>\n<div id=\"eip-id1165133032876\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}f\\left(0\\right)=\\left(0 - 2\\right)\\left(0+1\\right)\\left(0 - 4\\right)\\hfill \\\\ \\text{ }=\\left(-2\\right)\\left(1\\right)\\left(-4\\right)\\hfill \\\\ \\text{ }=8\\hfill \\end{cases}\\\\[\/latex]<\/div>\n<p id=\"fs-id1165135689436\">The <em>y-<\/em>intercept is (0, 8).<\/p>\n<p id=\"fs-id1165137863224\">The <em>x<\/em>-intercepts occur when the output is zero.<\/p>\n<div id=\"eip-id1165134380311\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}\\text{ }0=\\left(x - 2\\right)\\left(x+1\\right)\\left(x - 4\\right)\\hfill \\\\ x - 2=0\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & x+1=0\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & x - 4=0\\hfill \\\\ \\text{ }x=2\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & \\text{ }x=-1\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & x=4 \\end{cases}[\/latex]<\/div>\n<p id=\"fs-id1165135316178\">The\u00a0<i>x<\/i>-intercepts are<\/p>\n<p>[latex]\\left(2,0\\right),\\left(-1,0\\right), \\text{and} \\left(4,0\\right).\\\\[\/latex]<\/p>\n<p>We can see these intercepts on the graph of the function shown in Figure 11.<\/p>\n<div style=\"width: 497px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201345\/CNX_Precalc_Figure_03_03_0182.jpg\" alt=\"Graph of f(x)=(x-2)(x+1)(x-4), which labels all the intercepts.\" width=\"487\" height=\"630\" \/><\/p>\n<p class=\"wp-caption-text\"><b>Figure 11<\/b><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div id=\"Example_03_03_09\" class=\"example\">\n<div id=\"fs-id1165137834894\" class=\"exercise\">\n<div id=\"fs-id1165137834896\" class=\"problem textbox shaded\">\n<h3>Example 9: Determining the Intercepts of a Polynomial Function with Factoring<\/h3>\n<p id=\"fs-id1165137628033\">Given the polynomial function [latex]f\\left(x\\right)={x}^{4}-4{x}^{2}-45,\\\\[\/latex] determine the <em>y<\/em>&#8211; and\u00a0<em>x<\/em>-intercepts.<\/p>\n<\/div>\n<div id=\"fs-id1165137634473\" class=\"solution textbox shaded\">\n<h3>Solution<\/h3>\n<p>The <em>y-<\/em>intercept occurs when the input is zero.<\/p>\n<div id=\"eip-id1165132943488\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases} \\\\ f\\left(0\\right)={\\left(0\\right)}^{4}-4{\\left(0\\right)}^{2}-45\\hfill \\hfill \\\\ \\text{ }=-45\\hfill \\end{cases}\\\\[\/latex]<\/div>\n<p id=\"fs-id1165135653967\">The <em>y-<\/em>intercept is [latex]\\left(0,-45\\right).[\/latex]<\/p>\n<p id=\"fs-id1165135152099\">The <em>x<\/em>-intercepts occur when the output is zero. To determine when the output is zero, we will need to factor the polynomial.<\/p>\n<div id=\"eip-id1165135376171\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}f\\left(x\\right)={x}^{4}-4{x}^{2}-45\\hfill \\\\ =\\left({x}^{2}-9\\right)\\left({x}^{2}+5\\right)\\hfill \\\\ =\\left(x - 3\\right)\\left(x+3\\right)\\left({x}^{2}+5\\right)\\hfill \\end{cases}[\/latex]<\/div>\n<div class=\"equation unnumbered\"><\/div>\n<div class=\"equation unnumbered\" style=\"text-align: center\"><\/div>\n<div id=\"eip-id1165135684199\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]0=\\left(x - 3\\right)\\left(x+3\\right)\\left({x}^{2}+5\\right)\\\\[\/latex]<\/div>\n<div class=\"equation unnumbered\" style=\"text-align: center\"><\/div>\n<div id=\"eip-id1165134383791\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}x - 3=0\\hfill & \\text{or}\\hfill & x+3=0\\hfill & \\text{or}\\hfill & {x}^{2}+5=0\\hfill \\\\ \\text{ }x=3\\hfill & \\text{or}\\hfill & \\text{ }x=-3\\hfill & \\text{or}\\hfill & \\text{(no real solution)}\\hfill \\end{cases}\\\\[\/latex]<\/div>\n<p id=\"fs-id1165135436471\">The <em>x<\/em>-intercepts are [latex]\\left(3,0\\right) \\text{and} \\left(-3,0\\right).[\/latex]<\/p>\n<p>We can see these intercepts on the graph of the function shown in Figure 12. We can see that the function is even because [latex]f\\left(x\\right)=f\\left(-x\\right).\\\\[\/latex]<\/p>\n<div style=\"width: 497px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201346\/CNX_Precalc_Figure_03_03_0192.jpg\" alt=\"Graph of f(x)=x^4-4x^2-45, which labels all the intercepts at (-3, 0), (3, 0), and (0, -45).\" width=\"487\" height=\"426\" \/><\/p>\n<p class=\"wp-caption-text\"><b>Figure 12<\/b><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"bcc-box bcc-success\">\n<h3>Try It 6<\/h3>\n<p id=\"fs-id1165137405244\">Given the polynomial function [latex]f\\left(x\\right)=2{x}^{3}-6{x}^{2}-20x,\\\\[\/latex] determine the <em>y<\/em>&#8211; and<em> x<\/em>-intercepts.<\/p>\n<p><a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a><\/p>\n<\/div>\n<\/section>\n<section id=\"fs-id1165134080932\">\n<h2>Comparing Smooth and Continuous Graphs<\/h2>\n<p id=\"fs-id1165137692509\">The degree of a polynomial function helps us to determine the number of <em>x<\/em>-intercepts and the number of turning points. A polynomial function of\u00a0<em>n<\/em>th degree is the product of <em>n<\/em>\u00a0factors, so it will have at most <em>n<\/em>\u00a0roots or zeros, or <em>x<\/em>-intercepts. The graph of the polynomial function of degree <em>n<\/em>\u00a0must have at most <em>n<\/em> \u2013 1\u00a0turning points. This means the graph has at most one fewer turning point than the degree of the polynomial or one fewer than the number of factors.<\/p>\n<p id=\"fs-id1165137657937\">A <strong>continuous function<\/strong> has no breaks in its graph: the graph can be drawn without lifting the pen from the paper. A <strong>smooth curve<\/strong> is a graph that has no sharp corners. The turning points of a smooth graph must always occur at rounded curves. The graphs of polynomial functions are both continuous and smooth.<\/p>\n<div id=\"fs-id1165137847104\" class=\"note textbox\">\n<h3 class=\"title\">A General Note: Intercepts and Turning Points of Polynomials<\/h3>\n<p id=\"fs-id1165137405499\">A polynomial of degree <em>n<\/em>\u00a0will have, at most, <em>n<\/em>\u00a0<em>x<\/em>-intercepts and <em>n<\/em> \u2013 1\u00a0turning points.<\/p>\n<\/div>\n<div id=\"Example_03_03_10\" class=\"example\">\n<div id=\"fs-id1165135237034\" class=\"exercise\">\n<div id=\"fs-id1165135237036\" class=\"problem textbox shaded\">\n<h3>Example 10: Determining the Number of Intercepts and Turning Points of a Polynomial<\/h3>\n<p id=\"fs-id1165134152759\">Without graphing the function, determine the local behavior of the function by finding the maximum number of <em>x<\/em>-intercepts and turning points for [latex]f\\left(x\\right)=-3{x}^{10}+4{x}^{7}-{x}^{4}+2{x}^{3}.\\\\[\/latex]<\/p>\n<\/div>\n<div id=\"fs-id1165135414339\" class=\"solution textbox shaded\">\n<h3>Solution<\/h3>\n<p id=\"fs-id1165135414341\">The polynomial has a degree of 10, so there are at most <em>n<\/em>\u00a0<em>x<\/em>-intercepts and at most <em>n<\/em>\u00a0\u2013 1 turning points.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"bcc-box bcc-success\">\n<h3>Try It 7<\/h3>\n<p>Without graphing the function, determine the maximum number of <em>x<\/em>-intercepts and turning points for [latex]f\\left(x\\right)=108 - 13{x}^{9}-8{x}^{4}+14{x}^{12}+2{x}^{3}\\\\[\/latex]<\/p>\n<p><a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a><\/p>\n<\/div>\n<div id=\"Example_03_03_11\" class=\"example\">\n<div class=\"exercise\">\n<div id=\"fs-id1165137435066\" class=\"problem textbox shaded\">\n<h3>Example 11: Drawing Conclusions about a Polynomial Function from the Graph<\/h3>\n<p>What can we conclude about the polynomial represented by the graph shown in the graph in Figure 13\u00a0based on its intercepts and turning points?<\/p>\n<div style=\"width: 497px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201347\/CNX_Precalc_Figure_03_03_0202.jpg\" alt=\"Graph of an even-degree polynomial.\" width=\"487\" height=\"367\" \/><\/p>\n<p class=\"wp-caption-text\"><b>Figure 13<\/b><\/p>\n<\/div>\n<\/div>\n<div id=\"fs-id1165137737264\" class=\"solution textbox shaded\">\n<h3>Solution<\/h3>\n<div style=\"width: 497px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201349\/CNX_Precalc_Figure_03_03_0212.jpg\" alt=\"Graph of an even-degree polynomial that denotes the turning points and intercepts.\" width=\"487\" height=\"368\" \/><\/p>\n<p class=\"wp-caption-text\"><b>Figure 14<\/b><\/p>\n<\/div>\n<p id=\"fs-id1165131926327\">The end behavior of the graph tells us this is the graph of an even-degree polynomial.\u00a0<span id=\"fs-id1165137883772\"><br \/>\n<\/span><\/p>\n<p id=\"fs-id1165135670389\">The graph has 2 <em>x<\/em>-intercepts, suggesting a degree of 2 or greater, and 3 turning points, suggesting a degree of 4 or greater. Based on this, it would be reasonable to conclude that the degree is even and at least 4.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"bcc-box bcc-success\">\n<h3>Try It 8<\/h3>\n<p>What can we conclude about the polynomial represented by Figure 15\u00a0based on its intercepts and turning points?<\/p>\n<div style=\"width: 497px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/924\/2015\/11\/25201350\/CNX_Precalc_Figure_03_03_0224.jpg\" alt=\"Graph of an odd-degree polynomial.\" width=\"487\" height=\"442\" \/><\/p>\n<p class=\"wp-caption-text\"><b>Figure 15<\/b><\/p>\n<\/div>\n<p><a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a><\/p>\n<\/div>\n<div id=\"Example_03_03_12\" class=\"example\">\n<div id=\"fs-id1165135184013\" class=\"exercise\">\n<div id=\"fs-id1165137725458\" class=\"problem textbox shaded\">\n<h3>Example 12: Drawing Conclusions about a Polynomial Function from the Factors<\/h3>\n<p id=\"fs-id1165135435639\">Given the function [latex]f\\left(x\\right)=-4x\\left(x+3\\right)\\left(x - 4\\right),\\\\[\/latex]\u00a0determine the local behavior.<\/p>\n<\/div>\n<div id=\"fs-id1165135457721\" class=\"solution textbox shaded\">\n<h3>Solution<\/h3>\n<p id=\"fs-id1165135457723\">The <em>y<\/em>-intercept is found by evaluating [latex]f\\left(0\\right).[\/latex]<\/p>\n<div id=\"eip-id1165134587897\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}f\\left(0\\right)=-4\\left(0\\right)\\left(0+3\\right)\\left(0 - 4\\right)\\hfill \\hfill \\\\ \\text{ }=0\\hfill \\end{cases}\\\\[\/latex]<\/div>\n<p id=\"fs-id1165135245749\">The <em>y<\/em>-intercept is [latex]\\left(0,0\\right).[\/latex]<\/p>\n<p id=\"fs-id1165135203755\">The <em>x<\/em>-intercepts are found by determining the zeros of the function.<\/p>\n<div id=\"eip-id1165135401630\" class=\"equation unnumbered\" style=\"text-align: center\">[latex]\\begin{cases}0=-4x\\left(x+3\\right)\\left(x - 4\\right)\\\\ x=0\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & x+3=0\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & x - 4=0\\hfill \\\\ x=0\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & \\text{ }x=-3\\hfill & \\hfill & \\text{or}\\hfill & \\hfill & \\text{ }x=4\\end{cases}\\\\[\/latex]<\/div>\n<p id=\"fs-id1165135431016\">The <em>x<\/em>-intercepts are [latex]\\left(0,0\\right),\\left(-3,0\\right) \\text{and} \\left(4,0\\right).[\/latex]<\/p>\n<p id=\"fs-id1165137472984\">The degree is 3 so the graph has at most 2 turning points.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"bcc-box bcc-success\">\n<h3>Try It 9<\/h3>\n<p id=\"fs-id1165137575431\">Given the function [latex]f\\left(x\\right)=0.2\\left(x - 2\\right)\\left(x+1\\right)\\left(x - 5\\right),\\\\[\/latex] determine the local behavior.<\/p>\n<p><a href=\"https:\/\/courses.candelalearning.com\/osprecalc\/chapter\/solutions-12\/\" target=\"_blank\">Solution<\/a><\/p>\n<\/div>\n<\/section>\n","protected":false},"author":276,"menu_order":6,"template":"","meta":{"_candela_citation":"[]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1266","chapter","type-chapter","status-publish","hentry"],"part":1238,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/chapters\/1266","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/wp\/v2\/users\/276"}],"version-history":[{"count":7,"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/chapters\/1266\/revisions"}],"predecessor-version":[{"id":2637,"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/chapters\/1266\/revisions\/2637"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/parts\/1238"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/chapters\/1266\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/wp\/v2\/media?parent=1266"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/pressbooks\/v2\/chapter-type?post=1266"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/wp\/v2\/contributor?post=1266"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/ivytech-collegealgebra\/wp-json\/wp\/v2\/license?post=1266"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}