{"id":7157,"date":"2014-06-20T16:24:36","date_gmt":"2014-06-20T16:24:36","guid":{"rendered":"https:\/\/schooltutoring.com\/help\/?p=7157"},"modified":"2014-12-02T08:25:28","modified_gmt":"2014-12-02T08:25:28","slug":"math-review-of-solving-quadratic-equations-by-completing-the-square","status":"publish","type":"post","link":"https:\/\/schooltutoring.com\/help\/math-review-of-solving-quadratic-equations-by-completing-the-square\/","title":{"rendered":"Math Review of Solving Quadratic Equations by Completing the Square"},"content":{"rendered":"<h3>Overview<\/h3>\n<p>Many quadratic equations can be solved by a process called \u201ccompleting the square.\u201d The process uses the definitions of square roots, as well as the principles of adding or subtracting constants.<\/p>\n<h3>Equations in the Form ax<sup>2<\/sup> = p<\/h3>\n<p>Equations in the form ax<sup>2<\/sup> = p are quadratic equations. Suppose the coefficient a is equal to 1, so that the equation is x<sup>2<\/sup> = p (and p is greater than 0, so that the problem has a real-number solution). The value of x will equal the square root of p, or \u221ap, using the radical). For example, if x<sup>2<\/sup> = 144, then x = 12, the square root of 144. Using the definition of square roots, there are 2 square roots of 144, 12, and -12, because 12\u221912 = 144, and -12\u2219-12 also equals 144. An easier way in symbol form is that \u221a144 = \u00b112. If the coefficient a is greater than 1, then the value of x will equal \u00b1\u221ap\/a. For example, suppose 3x<sup>2<\/sup> = 75. Then x \u00b1 \u221a75\/3, or x \u00b15.<\/p>\n<p>Figure 1: Solving for x when x is squared<\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/Solving-equations.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-6954 aligncenter\" alt=\"monohybridcross\" src=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/Solving-equations.png\" width=\"300\" height=\"157\" \/><\/a><\/p>\n<h3>Equations in the Form (x + c)<sup>2<\/sup> = d<\/h3>\n<p>Equations in the form (x + c)<sup>2<\/sup> = d are also quadratic equations in the form of perfect square trinomials. The simplest way to solve them is by using the definition of square roots. Suppose that (x + 4)<sup>2<\/sup> = 36. Then, by the definition of square roots, x + 4 \u00b1 6. If 6 is positive, then x equals 2, but if 6 is negative, then x = -10. Suppose that the perfect square trinomial were expanded so that x<sup>2<\/sup> + 8x + 16 = 36. The solutions for x would still be 2 and -10, because if x = 2, then 4 + 16 + 16 = 36. Similarly, 100 &#8211; 80 + 16 = 36.<\/p>\n<p>Figure 2: Use the definition of square roots to solve perfect square trinomials.<\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/Perfect-square-trinomial.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-6954 aligncenter\" alt=\"monohybridcross\" src=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/Perfect-square-trinomial.png\" width=\"300\" height=\"157\" \/><\/a><\/p>\n<h3>Completing the Square<\/h3>\n<p>Suppose the equation were x<sup>2<\/sup> + 6x + 8 = 0. It is not a perfect square trinomial like x<sup>2<\/sup> + 8x + 16. When the coefficient for the x<sup>2<\/sup> term is 1, half of the b coefficient (for the x term) is squared to form the c coefficient. In the perfect square trinomial x<sup>2<\/sup> + 8x + 16, for example, half of 8 is 4, and 4<sup>2<\/sup> is 16. That property, as well as addition rules in algebra, can be used to complete the square. The first step is to turn the equation into a form that can be used to complete the square by moving the c term to the other side of the equation. This turns x<sup>2 <\/sup> + 6x + 8 = 0 to x<sup>2<\/sup> + 6x = -8, by subtracting 8 from both sides. If the equation were a perfect square trinomial, half of the b coefficient would be squared to form the c coefficient. The b coefficient in this equation is 6, and half of 6 is 3. The c term is 3<sup>2<\/sup> or 9. Using the addition rules of algebra, 9 can be added to <strong>both <\/strong>sides of the equation to form x<sup>2<\/sup> + 6x <strong>+9 <\/strong>= -8 <strong>+9<\/strong>. Factoring the left side of the equation, (x + 3)<sup>2<\/sup> = 1. Therefore, x +3 =\u00b1\u221a1. <strong>It is very important to remember that a number has a positive and a negative square root in order to solve both values of x.<\/strong> If the square root of x is positive, then x + 3 = 1, so x = -2. If the square root of x is negative, then x + 3 = -1, so x = -4.<\/p>\n<p>Figure 3: The path to completing a square.<\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/Completing-the-Square.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-6954 aligncenter\" alt=\"monohybridcross\" src=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/Completing-the-Square.png\" width=\"300\" height=\"157\" \/><\/a><\/p>\n<h3>Geometric Representation of Completing the Square<\/h3>\n<p>Another way of looking at completing the square is by looking at the geometric representation of how a square is completed. The equation x<sup>2<\/sup> + bx = a (which is the same equation as when the c term is moved), can be seen as a geometric figure that consists of a square with sides x and two rectangles with sides bx. The \u201cmissing piece\u201d that is completed is a square that has both sides equal to b\/2.<\/p>\n<p>Figure 4: Another way to look at completing the square.<\/p>\n<p style=\"text-align: center;\"><a href=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/geometric-representation-of-completing-the-square.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-6954 aligncenter\" alt=\"monohybridcross\" src=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/06\/geometric-representation-of-completing-the-square.png\" width=\"300\" height=\"157\" \/><\/a><\/p>\n<p>Interested in <a href=\"https:\/\/schooltutoring.com\/math-tutoring\/algebra-1-tutoring\/\">algebra tutoring services<\/a>? Learn more about how we are assisting thousands of students each academic year.<\/p>\n<p><span class=\"tutorOrange\">SchoolTutoring Academy<\/span> is the premier educational services company for K-12 and college students. We offer tutoring programs for\u00a0 students in K-12, AP classes, and college. To learn more about how we help parents and students in Nanaimo, BC, Canada: visit <a href=\"https:\/\/schooltutoring.com\/tutoring-in-nanaimo-british-columbia\/\">Tutoring in Nanaimo, BC, Canada<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview Many quadratic equations can be solved by a process called \u201ccompleting the square.\u201d The process uses the definitions of square roots, as well as the principles of adding or subtracting constants. Equations in the Form ax2 = p Equations in the form ax2 = p are quadratic equations. Suppose the coefficient a is equal [&hellip;]<\/p>\n","protected":false},"author":22,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[2],"tags":[339,1716],"class_list":["post-7157","post","type-post","status-publish","format-standard","hentry","category-algebra","tag-completing-the-square","tag-square-roots"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/7157","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/comments?post=7157"}],"version-history":[{"count":0,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/7157\/revisions"}],"wp:attachment":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/media?parent=7157"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/categories?post=7157"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/tags?post=7157"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}