How to identify family of function from given property












2














A={$f:Rto R$}



with following properties



f has derivative of every order



$forall x,yin R$ $f(x+y)-f(y-x)=2xf'(y)$



then I have to find whole family



Till now I just able to show $f(x)-f(-x)/2x=2xf'(0)$



I wanted to solve this problem.



Please provide just hint..



Thanks in Advanced










share|cite|improve this question






















  • Plug $y = x$ into the equation and use Taylor series ($f$ has a Taylor series since it's infinitely differentiable).
    – Rchn
    Nov 27 at 13:46












  • Sir I have done that , I got f(y)=f(0)+yf'(y/2).
    – MathLover
    Nov 27 at 13:53










  • form here how I one identify given family is polynomial of degree less than 2
    – MathLover
    Nov 27 at 13:54
















2














A={$f:Rto R$}



with following properties



f has derivative of every order



$forall x,yin R$ $f(x+y)-f(y-x)=2xf'(y)$



then I have to find whole family



Till now I just able to show $f(x)-f(-x)/2x=2xf'(0)$



I wanted to solve this problem.



Please provide just hint..



Thanks in Advanced










share|cite|improve this question






















  • Plug $y = x$ into the equation and use Taylor series ($f$ has a Taylor series since it's infinitely differentiable).
    – Rchn
    Nov 27 at 13:46












  • Sir I have done that , I got f(y)=f(0)+yf'(y/2).
    – MathLover
    Nov 27 at 13:53










  • form here how I one identify given family is polynomial of degree less than 2
    – MathLover
    Nov 27 at 13:54














2












2








2







A={$f:Rto R$}



with following properties



f has derivative of every order



$forall x,yin R$ $f(x+y)-f(y-x)=2xf'(y)$



then I have to find whole family



Till now I just able to show $f(x)-f(-x)/2x=2xf'(0)$



I wanted to solve this problem.



Please provide just hint..



Thanks in Advanced










share|cite|improve this question













A={$f:Rto R$}



with following properties



f has derivative of every order



$forall x,yin R$ $f(x+y)-f(y-x)=2xf'(y)$



then I have to find whole family



Till now I just able to show $f(x)-f(-x)/2x=2xf'(0)$



I wanted to solve this problem.



Please provide just hint..



Thanks in Advanced







real-analysis derivatives






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 27 at 13:28









MathLover

45710




45710












  • Plug $y = x$ into the equation and use Taylor series ($f$ has a Taylor series since it's infinitely differentiable).
    – Rchn
    Nov 27 at 13:46












  • Sir I have done that , I got f(y)=f(0)+yf'(y/2).
    – MathLover
    Nov 27 at 13:53










  • form here how I one identify given family is polynomial of degree less than 2
    – MathLover
    Nov 27 at 13:54


















  • Plug $y = x$ into the equation and use Taylor series ($f$ has a Taylor series since it's infinitely differentiable).
    – Rchn
    Nov 27 at 13:46












  • Sir I have done that , I got f(y)=f(0)+yf'(y/2).
    – MathLover
    Nov 27 at 13:53










  • form here how I one identify given family is polynomial of degree less than 2
    – MathLover
    Nov 27 at 13:54
















Plug $y = x$ into the equation and use Taylor series ($f$ has a Taylor series since it's infinitely differentiable).
– Rchn
Nov 27 at 13:46






Plug $y = x$ into the equation and use Taylor series ($f$ has a Taylor series since it's infinitely differentiable).
– Rchn
Nov 27 at 13:46














Sir I have done that , I got f(y)=f(0)+yf'(y/2).
– MathLover
Nov 27 at 13:53




Sir I have done that , I got f(y)=f(0)+yf'(y/2).
– MathLover
Nov 27 at 13:53












form here how I one identify given family is polynomial of degree less than 2
– MathLover
Nov 27 at 13:54




form here how I one identify given family is polynomial of degree less than 2
– MathLover
Nov 27 at 13:54















active

oldest

votes











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%2f3015766%2fhow-to-identify-family-of-function-from-given-property%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown






























active

oldest

votes













active

oldest

votes









active

oldest

votes






active

oldest

votes
















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.





Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


Please pay close attention to the following guidance:


  • 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.


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%2f3015766%2fhow-to-identify-family-of-function-from-given-property%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

How do I know what Microsoft account the skydrive app is syncing to?

Grease: Live!

When does type information flow backwards in C++?