{"id":7343,"date":"2014-08-06T22:41:54","date_gmt":"2014-08-06T22:41:54","guid":{"rendered":"https:\/\/schooltutoring.com\/help\/?p=7343"},"modified":"2014-12-02T08:25:26","modified_gmt":"2014-12-02T08:25:26","slug":"solving-integrals-through-the-use-of-integration-by-parts","status":"publish","type":"post","link":"https:\/\/schooltutoring.com\/help\/solving-integrals-through-the-use-of-integration-by-parts\/","title":{"rendered":"Solving Integrals Through the Use of Integration by Parts"},"content":{"rendered":"<h3>Overview<\/h3>\n<p>Suppose we have an integral which appears unsolvable by ordinary means, such as<br \/>\n\u222bxsin(x)dx In many cases, we can do what is called integration by parts, which is where we split the equation we are taking the integral of into two parts, with the goal of simplifying the equation such that we can reduce it down to an equation we know how to solve.<\/p>\n<h3>Formula<\/h3>\n<p>Figure 1: General formula for Integration by Parts<\/p>\n<p><a href=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/08\/IntByParts.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-medium wp-image-7348\" src=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/08\/IntByParts-300x30.png\" alt=\"IntByParts\" width=\"300\" height=\"30\" srcset=\"https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/08\/IntByParts-300x30.png 300w, https:\/\/schooltutoring.com\/help\/wp-content\/uploads\/sites\/2\/2014\/08\/IntByParts.png 370w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>In essence, what this means is that we are going to attempt to split up the equation in a way such that we can eliminate one of the equations inside the integral, allowing us to end up with a form that we know how to solve.<\/p>\n<h3>Examples<\/h3>\n<p>\u222bxsin(x)dx<br \/>\nLet u(x)=x and v\u2019(x)=sin(x)<br \/>\nThen we need to find u\u2019(x) and v(x), so u\u2019(x) = d\/dx(x) = 1<br \/>\nNext, we need to find v(x), which we do by doing \u222bv\u2019(x)dx, or in this case, \u222bsin(x)dx = -cos(x)<br \/>\nNow that we have u(x), v(x), u\u2019(x), and v\u2019(x), we can plug everything in, resulting in the following:<br \/>\n\u222bxsin(x)dx = x*(-cos(x)) &#8211; \u222b1*(-cos(x))dx<br \/>\n= -xcos(x)+\u222bcos(x)dx<br \/>\n= -xcos(x)+sin(x)+C<\/p>\n<p>In general, we will want to treat the polynomial as u(x) and the other team as v(x) where possible. In addition, Integration by Parts can be done multiple times. Suppose we have the equation<\/p>\n<p>\u222bx<sup>3<\/sup>e<sup>x<\/sup>dx<br \/>\nThen we will let u(x) = x<sup>3<\/sup> and v\u2019(x) = e<sup>x<\/sup>, then u\u2019(x) = 3x<sup>2<\/sup> and v(x)=e<sup>x<\/sup>, and we find that<br \/>\n\u222bx<sup>3<\/sup>e<sup>x<\/sup>dx = x<sup>3<\/sup>e<sup>x<\/sup> &#8211; \u222b3x<sup>2<\/sup>e<sup>x<\/sup>dx<br \/>\nThen we can do the same procedure with the slightly easier integral \u222b3x<sup>2<\/sup>e<sup>x<\/sup>dx<br \/>\nLet u(x) = 3x<sup>2<\/sup> and v\u2019(x) = e<sup>x<\/sup>, then u\u2019(x) = 6x and v(x) = e<sup>x<\/sup><br \/>\nThen \u222bx<sup>3<\/sup>e<sup>x<\/sup>dx = x<sup>3<\/sup>e<sup>x<\/sup> &#8211; \u222b3x<sup>2<\/sup>e<sup>x<\/sup>dx = x<sup>3<\/sup>e<sup>x<\/sup> &#8211; (3x<sup>2<\/sup>e<sup>x<\/sup> &#8211; \u222b6xe<sup>x<\/sup>dx)<br \/>\nAnd then with \u222b6xe<sup>x<\/sup>dx, we split it one last time into u(x) = 6x, v\u2019(x) = e<sup>x<\/sup>, and therefore u\u2019(x) = 6 and v(x) = e<sup>x<\/sup><br \/>\nThen we can substitute in one last time in order to get \u222b6xe<sup>x<\/sup>dx<br \/>\n\u222bx<sup>3<\/sup>e<sup>x<\/sup>dx = x<sup>3<\/sup>e<sup>x<\/sup> &#8211; \u222b3x<sup>2<\/sup>e<sup>x<\/sup>dx = x<sup>3<\/sup>e<sup>x<\/sup> &#8211; (3x<sup>2<\/sup>e<sup>x<\/sup> &#8211; (6xe<sup>x<\/sup> &#8211; \u222b6e<sup>x<\/sup>dx)) =<br \/>\nx<sup>3<\/sup>e<sup>x<\/sup> &#8211; 3x<sup>2<\/sup>e<sup>x<\/sup> + 6xe<sup>x<\/sup> &#8211; 6e<sup>x<\/sup> + C. Whew!<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>Interested in <a href=\"https:\/\/schooltutoring.com\/math-tutoring\/calculus-tutoring\/\">calculus 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 students in K-12, AP classes, and college. To learn more about how we help parents and students in Cumberland, MD: visit <a href=\"https:\/\/schooltutoring.com\/tutoring-in-cumberland-maryland\/\">Tutoring in Cumberland, MD<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview Suppose we have an integral which appears unsolvable by ordinary means, such as \u222bxsin(x)dx In many cases, we can do what is called integration by parts, which is where we split the equation we are taking the integral of into two parts, with the goal of simplifying the equation such that we can reduce [&hellip;]<\/p>\n","protected":false},"author":29,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[4],"tags":[2784,2785,2786],"class_list":["post-7343","post","type-post","status-publish","format-standard","hentry","category-calculus","tag-integral","tag-integration-by-parts","tag-simplifying-equations"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/7343","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\/29"}],"replies":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/comments?post=7343"}],"version-history":[{"count":0,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/7343\/revisions"}],"wp:attachment":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/media?parent=7343"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/categories?post=7343"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/tags?post=7343"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}