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[o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Skrá inn</span></a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Síður fyrir útskráða notendur <a href="/wiki/Hj%C3%A1lp:Introduction" aria-label="Læra meira um breytingar"><span>Læra meira</span></a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Kerfiss%C3%AD%C3%B0a:Framl%C3%B6g_m%C3%ADn" title="Listi yfir breytingar frá þessu IP-staðfangi [y]" accesskey="y"><span>Framlög</span></a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Kerfiss%C3%AD%C3%B0a:Spjallas%C3%AD%C3%B0a_m%C3%ADn" title="Spjall um breytingar frá þessu IP-staðfangi [n]" accesskey="n"><span>Spjall</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Vefsíða"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Efni" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Efni</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">færa í hliðarstiku</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">fela</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">Byrjun</div> </a> </li> <li id="toc-Tengt_efni" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Tengt_efni"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Tengt efni</span> </div> </a> <ul id="toc-Tengt_efni-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Ytri_tenglar" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Ytri_tenglar"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Ytri tenglar</span> </div> </a> <ul id="toc-Ytri_tenglar-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Heimildir" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Heimildir"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Heimildir</span> </div> </a> <ul id="toc-Heimildir-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Efni" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Sýna/fela efnisyfirlit" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Sýna/fela efnisyfirlit</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Rætt fall</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Fara á grein á öðru tungumáli. Til staðar á 42 tungumálum" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-42" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">42 tungumál</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AF%D8%A7%D9%84%D8%A9_%D9%83%D8%B3%D8%B1%D9%8A%D8%A9" title="دالة كسرية – arabíska" lang="ar" hreflang="ar" data-title="دالة كسرية" data-language-autonym="العربية" data-language-local-name="arabíska" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%AE%E0%A7%82%E0%A6%B2%E0%A6%A6%E0%A7%80%E0%A6%AF%E0%A6%BC_%E0%A6%85%E0%A6%AA%E0%A7%87%E0%A6%95%E0%A7%8D%E0%A6%B7%E0%A6%95" title="মূলদীয় অপেক্ষক – bengalska" lang="bn" hreflang="bn" data-title="মূলদীয় অপেক্ষক" data-language-autonym="বাংলা" data-language-local-name="bengalska" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Funci%C3%B3_racional" title="Funció racional – katalónska" lang="ca" hreflang="ca" data-title="Funció racional" data-language-autonym="Català" data-language-local-name="katalónska" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Racion%C3%A1ln%C3%AD_funkce" title="Racionální funkce – tékkneska" lang="cs" hreflang="cs" data-title="Racionální funkce" data-language-autonym="Čeština" data-language-local-name="tékkneska" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%A0%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%B0%D0%BB%D0%BB%C4%83_%D1%84%D1%83%D0%BD%D0%BA%D1%86%D0%B8" title="Рационаллă функци – sjúvas" lang="cv" hreflang="cv" data-title="Рационаллă функци" data-language-autonym="Чӑвашла" data-language-local-name="sjúvas" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Rationale_Funktion" title="Rationale Funktion – þýska" lang="de" hreflang="de" data-title="Rationale Funktion" data-language-autonym="Deutsch" data-language-local-name="þýska" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A1%CE%B7%CF%84%CE%AE_%CF%83%CF%85%CE%BD%CE%AC%CF%81%CF%84%CE%B7%CF%83%CE%B7" title="Ρητή συνάρτηση – gríska" lang="el" hreflang="el" data-title="Ρητή συνάρτηση" data-language-autonym="Ελληνικά" data-language-local-name="gríska" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-en mw-list-item"><a href="https://en.wikipedia.org/wiki/Rational_function" title="Rational function – enska" lang="en" hreflang="en" data-title="Rational function" data-language-autonym="English" data-language-local-name="enska" class="interlanguage-link-target"><span>English</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Racionala_funkcio" title="Racionala funkcio – esperantó" lang="eo" hreflang="eo" data-title="Racionala funkcio" data-language-autonym="Esperanto" data-language-local-name="esperantó" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Funci%C3%B3n_racional" title="Función racional – spænska" lang="es" hreflang="es" data-title="Función racional" data-language-autonym="Español" data-language-local-name="spænska" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%AA%D8%A7%D8%A8%D8%B9_%DA%AF%D9%88%DB%8C%D8%A7" title="تابع گویا – persneska" lang="fa" hreflang="fa" data-title="تابع گویا" data-language-autonym="فارسی" data-language-local-name="persneska" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Rationaalifunktio" title="Rationaalifunktio – finnska" lang="fi" hreflang="fi" data-title="Rationaalifunktio" data-language-autonym="Suomi" data-language-local-name="finnska" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Fonction_rationnelle" title="Fonction rationnelle – franska" lang="fr" hreflang="fr" data-title="Fonction rationnelle" data-language-autonym="Français" data-language-local-name="franska" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Funci%C3%B3n_racional" title="Función racional – galisíska" lang="gl" hreflang="gl" data-title="Función racional" data-language-autonym="Galego" data-language-local-name="galisíska" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A4%D7%95%D7%A0%D7%A7%D7%A6%D7%99%D7%94_%D7%A8%D7%A6%D7%99%D7%95%D7%A0%D7%9C%D7%99%D7%AA" title="פונקציה רציונלית – hebreska" lang="he" hreflang="he" data-title="פונקציה רציונלית" data-language-autonym="עברית" data-language-local-name="hebreska" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Racion%C3%A1lis_t%C3%B6rtf%C3%BCggv%C3%A9ny" title="Racionális törtfüggvény – ungverska" lang="hu" hreflang="hu" data-title="Racionális törtfüggvény" data-language-autonym="Magyar" data-language-local-name="ungverska" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%8C%D5%A1%D6%81%D5%AB%D5%B8%D5%B6%D5%A1%D5%AC_%D6%86%D5%B8%D6%82%D5%B6%D5%AF%D6%81%D5%AB%D5%A1" title="Ռացիոնալ ֆունկցիա – armenska" lang="hy" hreflang="hy" data-title="Ռացիոնալ ֆունկցիա" data-language-autonym="Հայերեն" data-language-local-name="armenska" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Fungsi_rasional" title="Fungsi rasional – indónesíska" lang="id" hreflang="id" data-title="Fungsi rasional" data-language-autonym="Bahasa Indonesia" data-language-local-name="indónesíska" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Funzione_razionale" title="Funzione razionale – ítalska" lang="it" hreflang="it" data-title="Funzione razionale" data-language-autonym="Italiano" data-language-local-name="ítalska" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E6%9C%89%E7%90%86%E9%96%A2%E6%95%B0" title="有理関数 – japanska" lang="ja" hreflang="ja" data-title="有理関数" data-language-autonym="日本語" data-language-local-name="japanska" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A0%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%B0%D0%BB_%D1%84%D1%83%D0%BD%D0%BA%D1%86%D0%B8%D1%8F" title="Рационал функция – kasakska" lang="kk" hreflang="kk" data-title="Рационал функция" data-language-autonym="Қазақша" data-language-local-name="kasakska" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%9C%A0%EB%A6%AC_%ED%95%A8%EC%88%98" title="유리 함수 – kóreska" lang="ko" hreflang="ko" data-title="유리 함수" data-language-autonym="한국어" data-language-local-name="kóreska" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Rational_Funktioun" title="Rational Funktioun – lúxemborgíska" lang="lb" hreflang="lb" data-title="Rational Funktioun" data-language-autonym="Lëtzebuergesch" data-language-local-name="lúxemborgíska" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%A0%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%B0%D0%BB%D0%BD%D0%B0_%D1%84%D1%83%D0%BD%D0%BA%D1%86%D0%B8%D1%98%D0%B0" title="Рационална функција – makedónska" lang="mk" hreflang="mk" data-title="Рационална функција" data-language-autonym="Македонски" data-language-local-name="makedónska" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Rationale_functie" title="Rationale functie – hollenska" lang="nl" hreflang="nl" data-title="Rationale functie" data-language-autonym="Nederlands" data-language-local-name="hollenska" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Rasjonal_funksjon" title="Rasjonal funksjon – nýnorska" lang="nn" hreflang="nn" data-title="Rasjonal funksjon" data-language-autonym="Norsk nynorsk" data-language-local-name="nýnorska" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Rasjonal_funksjon" title="Rasjonal funksjon – norskt bókmál" lang="nb" hreflang="nb" data-title="Rasjonal funksjon" data-language-autonym="Norsk bokmål" data-language-local-name="norskt bókmál" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Funkcja_wymierna" title="Funkcja wymierna – pólska" lang="pl" hreflang="pl" data-title="Funkcja wymierna" data-language-autonym="Polski" data-language-local-name="pólska" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Fun%C3%A7%C3%A3o_racional" title="Função racional – portúgalska" lang="pt" hreflang="pt" data-title="Função racional" data-language-autonym="Português" data-language-local-name="portúgalska" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Func%C8%9Bie_ra%C8%9Bional%C4%83" title="Funcție rațională – rúmenska" lang="ro" hreflang="ro" data-title="Funcție rațională" data-language-autonym="Română" data-language-local-name="rúmenska" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A0%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%B0%D0%BB%D1%8C%D0%BD%D0%B0%D1%8F_%D1%84%D1%83%D0%BD%D0%BA%D1%86%D0%B8%D1%8F" title="Рациональная функция – rússneska" lang="ru" hreflang="ru" data-title="Рациональная функция" data-language-autonym="Русский" data-language-local-name="rússneska" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Rational_function" title="Rational function – Simple English" lang="en-simple" hreflang="en-simple" data-title="Rational function" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Racion%C3%A1lna_funkcia" title="Racionálna funkcia – slóvakíska" lang="sk" hreflang="sk" data-title="Racionálna funkcia" data-language-autonym="Slovenčina" data-language-local-name="slóvakíska" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a 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<div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="is" dir="ltr"><figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/Mynd:RationalDegree2byXedi.gif" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/09/RationalDegree2byXedi.gif/250px-RationalDegree2byXedi.gif" decoding="async" width="250" height="208" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/0/09/RationalDegree2byXedi.gif 1.5x" data-file-width="300" data-file-height="250" /></a><figcaption>Hérna er fallið <br /> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle y={\frac {x^{2}-3x-2}{x^{2}-4}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>y</mi> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>−</mo> <mn>3</mn> <mi>x</mi> <mo>−</mo> <mn>2</mn> </mrow> <mrow> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>−</mo> <mn>4</mn> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle y={\frac {x^{2}-3x-2}{x^{2}-4}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f34422d5e504da2510ad790b946b2af8d5515976" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:16.809ex; height:6.176ex;" alt="{\displaystyle y={\frac {x^{2}-3x-2}{x^{2}-4}}}"></span><br />teiknað en það er rætt fall af annarri gráðu.</figcaption></figure> <p><b>Rætt fall</b> er <a href="/wiki/Fall_(st%C3%A6r%C3%B0fr%C3%A6%C3%B0i)" title="Fall (stærðfræði)">fall</a>, sem er <a href="/wiki/Hlutfall" title="Hlutfall">hlutfall</a> tveggja <a href="/wiki/Margli%C3%B0ufall" class="mw-redirect" title="Margliðufall">margliðufalla</a>. Þegar margliðufall er skilgreint fyrir eina <a href="/wiki/Breyta" title="Breyta">breytu</a> <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>x</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle x\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ab34739435d9d9d99cddf4041740b107343b1398" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.717ex; height:1.676ex;" alt="{\displaystyle x\,}"></span> þá er rætt fall táknað á forminu </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)={\frac {P_{m}(x)}{Q_{n}(x)}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>f</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <msub> <mi>Q</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle f(x)={\frac {P_{m}(x)}{Q_{n}(x)}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/02665092d80c9d5d575f8c660c76ec0612d173c1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:14.658ex; height:6.509ex;" alt="{\displaystyle f(x)={\frac {P_{m}(x)}{Q_{n}(x)}}}"></span></dd></dl> <p>þar sem <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle P\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>P</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle P\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f60e07ebc2aadee94e4cbbccef71fd9bcf44f5f9" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.133ex; height:2.176ex;" alt="{\displaystyle P\,}"></span> og <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Q\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>Q</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Q\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b23c85e3da723c6f662dfd28b9ea209f3f0df613" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.225ex; height:2.509ex;" alt="{\displaystyle Q\,}"></span> tákna <a href="/wiki/Margli%C3%B0ufall" class="mw-redirect" title="Margliðufall">margliðuföllin</a> </p><p><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle P_{m}(x)=a_{m}x^{m}+a_{m-1}x^{m-1}+\cdots +a_{2}x^{2}+a_{1}x+a_{0}\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mo>=</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> </mrow> </msub> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> </mrow> </msup> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> <mo>−</mo> <mn>1</mn> </mrow> </msub> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <mo>⋯</mo> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mi>x</mi> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle P_{m}(x)=a_{m}x^{m}+a_{m-1}x^{m-1}+\cdots +a_{2}x^{2}+a_{1}x+a_{0}\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/868da254515bde6f7d7743cba131878e30aa60b6" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:53.303ex; height:3.176ex;" alt="{\displaystyle P_{m}(x)=a_{m}x^{m}+a_{m-1}x^{m-1}+\cdots +a_{2}x^{2}+a_{1}x+a_{0}\,}"></span> og <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Q_{n}(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+\cdots +a_{2}x^{2}+a_{1}x+a_{0}\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>Q</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mo>=</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msup> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> <mo>−</mo> <mn>1</mn> </mrow> </msub> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> <mo>−</mo> <mn>1</mn> </mrow> </msup> <mo>+</mo> <mo>⋯</mo> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> <msup> <mi>x</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mi>x</mi> <mo>+</mo> <msub> <mi>a</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>0</mn> </mrow> </msub> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Q_{n}(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+\cdots +a_{2}x^{2}+a_{1}x+a_{0}\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/9e1d4f66bf0e0b9e33cb69934dd4af7d2af45c0a" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:51.366ex; height:3.176ex;" alt="{\displaystyle Q_{n}(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+\cdots +a_{2}x^{2}+a_{1}x+a_{0}\,}"></span> og <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Q_{n}(x)\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>Q</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Q_{n}(x)\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b99f7c0019580143bccddc9176b473a0e5bd115b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:6.583ex; height:2.843ex;" alt="{\displaystyle Q_{n}(x)\,}"></span> er ekki <a href="/wiki/N%C3%BAllmargli%C3%B0a" class="mw-redirect" title="Núllmargliða">núllmargliða</a>. </p><p>Ræða fallið <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)={\frac {P_{m}(x)}{Q_{n}(x)}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>f</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <msub> <mi>Q</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle f(x)={\frac {P_{m}(x)}{Q_{n}(x)}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/02665092d80c9d5d575f8c660c76ec0612d173c1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:14.658ex; height:6.509ex;" alt="{\displaystyle f(x)={\frac {P_{m}(x)}{Q_{n}(x)}}}"></span> nefnist svo <b>eiginlegt</b> ef <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>m</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle m\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/37129e832c2c81b9f146dd22228d409bd099b295" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.427ex; height:1.676ex;" alt="{\displaystyle m\,}"></span> sem er gráða margliðunnar <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle P_{m}(x)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>P</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>m</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle P_{m}(x)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/fb1147a6ef62fb89d969335d1ef46427c24f133e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:6.306ex; height:2.843ex;" alt="{\displaystyle P_{m}(x)}"></span> er lægri en <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>n</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/205e33e6845813cc72ca346b896a7945f90ca373" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.782ex; height:1.676ex;" alt="{\displaystyle n\,}"></span> sem er gráða margliðunnar <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Q_{n}(x)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>Q</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>n</mi> </mrow> </msub> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Q_{n}(x)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2a5eab5a40e5daf0466f67130cc14c1436a28777" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:6.196ex; height:2.843ex;" alt="{\displaystyle Q_{n}(x)}"></span>. Ef <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>m</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle m\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/37129e832c2c81b9f146dd22228d409bd099b295" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.427ex; height:1.676ex;" alt="{\displaystyle m\,}"></span> er hins vegar hærra en <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle n\,}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>n</mi> <mspace width="thinmathspace" /> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle n\,}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/205e33e6845813cc72ca346b896a7945f90ca373" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.782ex; height:1.676ex;" alt="{\displaystyle n\,}"></span> kallast fallið <b>óeiginlegt</b>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p>Umrita má rætt fall með <a href="/wiki/Margli%C3%B0udeiling" title="Margliðudeiling">margliðudeilingu</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Tengt_efni">Tengt efni</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=R%C3%A6tt_fall&veaction=edit&section=1" title="Breyti hluta: Tengt efni" class="mw-editsection-visualeditor"><span>breyta</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=R%C3%A6tt_fall&action=edit&section=1" title="Edit section's source code: Tengt efni"><span>breyta frumkóða</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Heilt_r%C3%A6tt_fall" class="mw-redirect" title="Heilt rætt fall">Heilt rætt fall</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Ytri_tenglar">Ytri tenglar</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=R%C3%A6tt_fall&veaction=edit&section=2" title="Breyti hluta: Ytri tenglar" class="mw-editsection-visualeditor"><span>breyta</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=R%C3%A6tt_fall&action=edit&section=2" title="Edit section's source code: Ytri tenglar"><span>breyta frumkóða</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="http://www.rasmus.is/Is/T/F/Su41k03.htm">Kynning 3- Aðfellur ræðra falla</a> á <a rel="nofollow" class="external free" href="http://www.rasmus.is/">http://www.rasmus.is/</a></li> <li><a rel="nofollow" class="external text" href="http://www.rasmus.is/Is/T/F/Su40k04.htm">Kynning 3- Ræð Föll</a> á <a rel="nofollow" class="external free" href="http://www.rasmus.is/">http://www.rasmus.is/</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Heimildir">Heimildir</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=R%C3%A6tt_fall&veaction=edit&section=3" title="Breyti hluta: Heimildir" class="mw-editsection-visualeditor"><span>breyta</span></a><span class="mw-editsection-divider"> | </span><a href="/w/index.php?title=R%C3%A6tt_fall&action=edit&section=3" title="Edit section's source code: Heimildir"><span>breyta frumkóða</span></a><span class="mw-editsection-bracket">]</span></span></div> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><a href="#cite_ref-1">↑</a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.verslo.is/home/KriJLei/St%C3%A6r%C3%B0fr%C3%A6%C3%B0i/St%C3%A6r%C3%B0fr%C3%A6%C3%B0i%20503%20-%20skilgreiningar.doc">Stærðfræði 503</a><sup>[<i><a href="https://en.wikipedia.org/wiki/Wikipedia:Link_rot" class="extiw" title="en:Wikipedia:Link rot">óvirkur tengill</a></i>]</sup></span> </li> </ol>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1&useformat=desktop" alt="" width="1" height="1" style="border: none; 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