{"id":1353,"date":"2017-10-30T16:20:28","date_gmt":"2017-10-30T20:20:28","guid":{"rendered":"http:\/\/blog.richmond.edu\/math320\/?p=1353"},"modified":"2017-10-30T16:20:28","modified_gmt":"2017-10-30T20:20:28","slug":"hw7-challenge-5","status":"publish","type":"post","link":"https:\/\/blog.richmond.edu\/math320\/2017\/10\/30\/hw7-challenge-5\/","title":{"rendered":"HW7: Challenge 5"},"content":{"rendered":"<p>Proof by Contradiction<\/p>\n<p>Suppose <img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f\" class=\"latex\" \/> is differentiable on an interval\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=A&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"A\" class=\"latex\" \/> with\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f%27%28x%29+%5Cneq+1&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f&#039;(x) &#92;neq 1\" class=\"latex\" \/>, and\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f\" class=\"latex\" \/> has more than 1 fixed point. Let\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=x%2Cy+%5Cin+A&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"x,y &#92;in A\" class=\"latex\" \/> such that\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=x%2Cy&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"x,y\" class=\"latex\" \/> are fixed points where\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=x+%5Cneq+y&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"x &#92;neq y\" class=\"latex\" \/>. By the definition of fixed point from Weekly HW 6,\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f%28x%29%3Dx&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f(x)=x\" class=\"latex\" \/> and\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f%28y%29%3Dy&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f(y)=y\" class=\"latex\" \/>. By Theorem 5.2.3, since\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f\" class=\"latex\" \/> is differentiable on\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=A&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"A\" class=\"latex\" \/>, then\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f\" class=\"latex\" \/> is continuous on\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=A&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"A\" class=\"latex\" \/>. Thus, we can apply the Mean Value Theorem so that there exists a\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=c+%5Cin+%28x%2Cy%29&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"c &#92;in (x,y)\" class=\"latex\" \/> such that\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f%27%28c%29%3D+%5Cfrac%7Bf%28y%29-f%28x%29%7D%7By-x%7D&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f&#039;(c)= &#92;frac{f(y)-f(x)}{y-x}\" class=\"latex\" \/>. By algebra,\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f%27%28c%29%3D%5Cfrac%7By-x%7D%7By-x%7D%3D1&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f&#039;(c)=&#92;frac{y-x}{y-x}=1\" class=\"latex\" \/>. This is a contradiction because\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f%27%28x%29+%5Cneq+1&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f&#039;(x) &#92;neq 1\" class=\"latex\" \/>. Thus,\u00a0<img decoding=\"async\" src=\"https:\/\/s0.wp.com\/latex.php?latex=f&#038;bg=ffffff&#038;fg=000&#038;s=0&#038;c=20201002\" alt=\"f\" class=\"latex\" \/> has at most one fixed point.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Proof by Contradiction Suppose is differentiable on an interval\u00a0 with\u00a0, and\u00a0 has more than 1 fixed point. Let\u00a0 such that\u00a0 are fixed points where\u00a0. By the definition of fixed point from Weekly HW 6,\u00a0 and\u00a0. By Theorem 5.2.3, since\u00a0 is differentiable on\u00a0, then\u00a0 is continuous on\u00a0. Thus, we can apply the Mean Value Theorem so [&hellip;]<\/p>\n","protected":false},"author":3530,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[58827,58826],"tags":[],"class_list":["post-1353","post","type-post","status-publish","format-standard","hentry","category-challenge-solutions","category-peer-grading"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p7L4E1-lP","jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/posts\/1353","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/users\/3530"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/comments?post=1353"}],"version-history":[{"count":0,"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/posts\/1353\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/media?parent=1353"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/categories?post=1353"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.richmond.edu\/math320\/wp-json\/wp\/v2\/tags?post=1353"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}