﻿{"id":5236,"date":"2014-04-21T06:05:54","date_gmt":"2014-04-20T21:05:54","guid":{"rendered":"http:\/\/fujiitoshiki.com\/improvesociety\/?p=5236"},"modified":"2014-08-01T18:33:30","modified_gmt":"2014-08-01T09:33:30","slug":"inverse-of-a-matrix","status":"publish","type":"post","link":"https:\/\/www.fujiitoshiki.com\/improvesociety\/?p=5236","title":{"rendered":"Inverse of a matrix"},"content":{"rendered":"<div class=\"theContentWrap-ccc\"><blockquote>\n<p>If for a given square matrix <img src='https:\/\/s0.wp.com\/latex.php?latex=A&#038;bg=T&#038;fg=000000&#038;s=0' alt='A' title='A' class='latex' \/> there exists a matrix <img src='https:\/\/s0.wp.com\/latex.php?latex=B&#038;bg=T&#038;fg=000000&#038;s=0' alt='B' title='B' class='latex' \/> such that <img src='https:\/\/s0.wp.com\/latex.php?latex=+AB+%3D+I+&#038;bg=T&#038;fg=000000&#038;s=0' alt=' AB = I ' title=' AB = I ' class='latex' \/>, then <img src='https:\/\/s0.wp.com\/latex.php?latex=B&#038;bg=T&#038;fg=000000&#038;s=0' alt='B' title='B' class='latex' \/> is called an <em>inverse<\/em> of <img src='https:\/\/s0.wp.com\/latex.php?latex=A&#038;bg=T&#038;fg=000000&#038;s=0' alt='A' title='A' class='latex' \/> and is denoted by <img src='https:\/\/s0.wp.com\/latex.php?latex=A%5E%7B-1%7D&#038;bg=T&#038;fg=000000&#038;s=0' alt='A^{-1}' title='A^{-1}' class='latex' \/>. The following theorem is fundamental. <\/p>\n<p>11. If <img src='https:\/\/s0.wp.com\/latex.php?latex=A&#038;bg=T&#038;fg=000000&#038;s=0' alt='A' title='A' class='latex' \/> is a non-singular square matrix of order <em>n<\/em> [i.e. <img src='https:\/\/s0.wp.com\/latex.php?latex=%5Cdet%28A%29+%5Cne+0&#038;bg=T&#038;fg=000000&#038;s=0' alt='\\det(A) \\ne 0' title='\\det(A) \\ne 0' class='latex' \/>], then there exists a unique inverse <img src='https:\/\/s0.wp.com\/latex.php?latex=A%5E%7B-1%7D&#038;bg=T&#038;fg=000000&#038;s=0' alt='A^{-1}' title='A^{-1}' class='latex' \/> such that <img src='https:\/\/s0.wp.com\/latex.php?latex=AA%5E%7B-1%7D+%3D+A%5E%7B-1%7DA+%3D+I+&#038;bg=T&#038;fg=000000&#038;s=0' alt='AA^{-1} = A^{-1}A = I ' title='AA^{-1} = A^{-1}A = I ' class='latex' \/> and we can express <img src='https:\/\/s0.wp.com\/latex.php?latex=+A%5E%7B-1%7D+&#038;bg=T&#038;fg=000000&#038;s=0' alt=' A^{-1} ' title=' A^{-1} ' class='latex' \/> in the following form <\/p>\n<p><img src='https:\/\/s0.wp.com\/latex.php?latex=%5Cdisplaystyle+A%5E%7B-1%7D+%3D+%5Cfrac%7B%28A_%7Bjk%7D%29%5ET%7D%7B%5Cdet%28A%29%7D+%5Ccdots%2814%29&#038;bg=T&#038;fg=000000&#038;s=0' alt='\\displaystyle A^{-1} = \\frac{(A_{jk})^T}{\\det(A)} \\cdots(14)' title='\\displaystyle A^{-1} = \\frac{(A_{jk})^T}{\\det(A)} \\cdots(14)' class='latex' \/><\/p>\n<p>where <img src='https:\/\/s0.wp.com\/latex.php?latex=%28A_%7Bjk%7D%29&#038;bg=T&#038;fg=000000&#038;s=0' alt='(A_{jk})' title='(A_{jk})' class='latex' \/> is the matrix of cofactors <img src='https:\/\/s0.wp.com\/latex.php?latex=A_%7Bjk%7D&#038;bg=T&#038;fg=000000&#038;s=0' alt='A_{jk}' title='A_{jk}' class='latex' \/> and <img src='https:\/\/s0.wp.com\/latex.php?latex=%28A_%7Bjk%7D%29%5ET+%3D+%28A_%7Bkj%7D%29&#038;bg=T&#038;fg=000000&#038;s=0' alt='(A_{jk})^T = (A_{kj})' title='(A_{jk})^T = (A_{kj})' class='latex' \/> is its transpose. <\/p>\n<p>The following express some properties of the inverse: <\/p>\n<p><img src='https:\/\/s0.wp.com\/latex.php?latex=%28AB%29%5E%7B-1%7D+%3D+B%5E%7B-1%7DA%5E%7B-1%7D+%2C%5C+%28A%5E%7B-1%7D%29%5E%7B-1%7D+%3D+A+%5Ccdots%2815%29&#038;bg=T&#038;fg=000000&#038;s=0' alt='(AB)^{-1} = B^{-1}A^{-1} ,\\ (A^{-1})^{-1} = A \\cdots(15)' title='(AB)^{-1} = B^{-1}A^{-1} ,\\ (A^{-1})^{-1} = A \\cdots(15)' class='latex' \/><\/p>\n<\/blockquote>\n<p><iframe src=\"\/\/rcm-fe.amazon-adsystem.com\/e\/cm?lt1=_blank&#038;bc1=000000&#038;IS2=1&#038;bg1=FFFFFF&#038;fc1=000000&#038;lc1=0000FF&#038;t=fujiitoshiki-22&#038;o=9&#038;p=8&#038;l=as4&#038;m=amazon&#038;f=ifr&#038;ref=ss_til&#038;asins=0071635408\" style=\"width:120px;height:240px;\" scrolling=\"no\" marginwidth=\"0\" marginheight=\"0\" frameborder=\"0\"><\/iframe><\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>If for a given square matrix there exists a matrix such that , then is called an inverse of and is denoted by  &hellip; <a href=\"https:\/\/www.fujiitoshiki.com\/improvesociety\/?p=5236\" class=\"more-link\"><span class=\"screen-reader-text\">&#8220;Inverse of a matrix&#8221; \u306e<\/span>\u7d9a\u304d\u3092\u8aad\u3080<\/a><\/p>\n","protected":false},"author":1,"featured_media":6040,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_crdt_document":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[9],"tags":[],"class_list":["post-5236","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-mathematics"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/posts\/5236","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5236"}],"version-history":[{"count":5,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/posts\/5236\/revisions"}],"predecessor-version":[{"id":5424,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/posts\/5236\/revisions\/5424"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=\/wp\/v2\/media\/6040"}],"wp:attachment":[{"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5236"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fujiitoshiki.com\/improvesociety\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}