Integrals of generally continuous functions: definition and example












0












$begingroup$


$f(x)$ is called "generally continuous functions" in $[a,b]$ if it is not continuous in a finite number of points of this interval.



Example: let $f(x) = dfrac{1}{|x-b|^alpha}$, with $alpha < 0$



To retrieve $displaystyle int_a^b f(x) dx$, I must retrieve $displaystyle int_a^{b+epsilon} f(x) dx$ with $epsilon < 0$. But



$$int_a^{b+epsilon} dfrac{1}{|x-b|^alpha} ; dx = int_a^{b+epsilon} dfrac{1}{(-x+b)^alpha} ; dx$$



I can't understand the last equality: how can I get $|x-b|^alpha$ from $(-x+b)^alpha$?










share|cite|improve this question









$endgroup$

















    0












    $begingroup$


    $f(x)$ is called "generally continuous functions" in $[a,b]$ if it is not continuous in a finite number of points of this interval.



    Example: let $f(x) = dfrac{1}{|x-b|^alpha}$, with $alpha < 0$



    To retrieve $displaystyle int_a^b f(x) dx$, I must retrieve $displaystyle int_a^{b+epsilon} f(x) dx$ with $epsilon < 0$. But



    $$int_a^{b+epsilon} dfrac{1}{|x-b|^alpha} ; dx = int_a^{b+epsilon} dfrac{1}{(-x+b)^alpha} ; dx$$



    I can't understand the last equality: how can I get $|x-b|^alpha$ from $(-x+b)^alpha$?










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      $f(x)$ is called "generally continuous functions" in $[a,b]$ if it is not continuous in a finite number of points of this interval.



      Example: let $f(x) = dfrac{1}{|x-b|^alpha}$, with $alpha < 0$



      To retrieve $displaystyle int_a^b f(x) dx$, I must retrieve $displaystyle int_a^{b+epsilon} f(x) dx$ with $epsilon < 0$. But



      $$int_a^{b+epsilon} dfrac{1}{|x-b|^alpha} ; dx = int_a^{b+epsilon} dfrac{1}{(-x+b)^alpha} ; dx$$



      I can't understand the last equality: how can I get $|x-b|^alpha$ from $(-x+b)^alpha$?










      share|cite|improve this question









      $endgroup$




      $f(x)$ is called "generally continuous functions" in $[a,b]$ if it is not continuous in a finite number of points of this interval.



      Example: let $f(x) = dfrac{1}{|x-b|^alpha}$, with $alpha < 0$



      To retrieve $displaystyle int_a^b f(x) dx$, I must retrieve $displaystyle int_a^{b+epsilon} f(x) dx$ with $epsilon < 0$. But



      $$int_a^{b+epsilon} dfrac{1}{|x-b|^alpha} ; dx = int_a^{b+epsilon} dfrac{1}{(-x+b)^alpha} ; dx$$



      I can't understand the last equality: how can I get $|x-b|^alpha$ from $(-x+b)^alpha$?







      definite-integrals






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 9 at 14:31









      user3204810user3204810

      1947




      1947






















          1 Answer
          1






          active

          oldest

          votes


















          1












          $begingroup$

          If $x in [a, b+epsilon]$ then $|x-b|=b-x$ since $x < b$.






          share|cite|improve this answer









          $endgroup$














            Your Answer





            StackExchange.ifUsing("editor", function () {
            return StackExchange.using("mathjaxEditing", function () {
            StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
            StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
            });
            });
            }, "mathjax-editing");

            StackExchange.ready(function() {
            var channelOptions = {
            tags: "".split(" "),
            id: "69"
            };
            initTagRenderer("".split(" "), "".split(" "), channelOptions);

            StackExchange.using("externalEditor", function() {
            // Have to fire editor after snippets, if snippets enabled
            if (StackExchange.settings.snippets.snippetsEnabled) {
            StackExchange.using("snippets", function() {
            createEditor();
            });
            }
            else {
            createEditor();
            }
            });

            function createEditor() {
            StackExchange.prepareEditor({
            heartbeatType: 'answer',
            autoActivateHeartbeat: false,
            convertImagesToLinks: true,
            noModals: true,
            showLowRepImageUploadWarning: true,
            reputationToPostImages: 10,
            bindNavPrevention: true,
            postfix: "",
            imageUploader: {
            brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
            contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
            allowUrls: true
            },
            noCode: true, onDemand: true,
            discardSelector: ".discard-answer"
            ,immediatelyShowMarkdownHelp:true
            });


            }
            });














            draft saved

            draft discarded


















            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3067505%2fintegrals-of-generally-continuous-functions-definition-and-example%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1












            $begingroup$

            If $x in [a, b+epsilon]$ then $|x-b|=b-x$ since $x < b$.






            share|cite|improve this answer









            $endgroup$


















              1












              $begingroup$

              If $x in [a, b+epsilon]$ then $|x-b|=b-x$ since $x < b$.






              share|cite|improve this answer









              $endgroup$
















                1












                1








                1





                $begingroup$

                If $x in [a, b+epsilon]$ then $|x-b|=b-x$ since $x < b$.






                share|cite|improve this answer









                $endgroup$



                If $x in [a, b+epsilon]$ then $|x-b|=b-x$ since $x < b$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Jan 9 at 14:38









                A. BailleulA. Bailleul

                1587




                1587






























                    draft saved

                    draft discarded




















































                    Thanks for contributing an answer to Mathematics Stack Exchange!


                    • Please be sure to answer the question. Provide details and share your research!

                    But avoid



                    • Asking for help, clarification, or responding to other answers.

                    • Making statements based on opinion; back them up with references or personal experience.


                    Use MathJax to format equations. MathJax reference.


                    To learn more, see our tips on writing great answers.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3067505%2fintegrals-of-generally-continuous-functions-definition-and-example%23new-answer', 'question_page');
                    }
                    );

                    Post as a guest















                    Required, but never shown





















































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown

































                    Required, but never shown














                    Required, but never shown












                    Required, but never shown







                    Required, but never shown







                    Popular posts from this blog

                    Bressuire

                    Cabo Verde

                    Gyllenstierna