A question related to the mean value theorem












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Let $f$ be continuous on $[a,b]$ and differentiable on $(a,b)$. It it true that for every $cin[a,b]$, there exists some $(a_0, b_0)$ such that



$$f'(c) = frac{f(b_0)-f(a_0)}{b_0 - a_0},? $$










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  • $begingroup$
    You need to ensure that there are no points of inflection for $f$ in $(a, b) $ otherwise the result is false.
    $endgroup$
    – Paramanand Singh
    Dec 20 '18 at 7:00
















0












$begingroup$


Let $f$ be continuous on $[a,b]$ and differentiable on $(a,b)$. It it true that for every $cin[a,b]$, there exists some $(a_0, b_0)$ such that



$$f'(c) = frac{f(b_0)-f(a_0)}{b_0 - a_0},? $$










share|cite|improve this question











$endgroup$












  • $begingroup$
    You need to ensure that there are no points of inflection for $f$ in $(a, b) $ otherwise the result is false.
    $endgroup$
    – Paramanand Singh
    Dec 20 '18 at 7:00














0












0








0





$begingroup$


Let $f$ be continuous on $[a,b]$ and differentiable on $(a,b)$. It it true that for every $cin[a,b]$, there exists some $(a_0, b_0)$ such that



$$f'(c) = frac{f(b_0)-f(a_0)}{b_0 - a_0},? $$










share|cite|improve this question











$endgroup$




Let $f$ be continuous on $[a,b]$ and differentiable on $(a,b)$. It it true that for every $cin[a,b]$, there exists some $(a_0, b_0)$ such that



$$f'(c) = frac{f(b_0)-f(a_0)}{b_0 - a_0},? $$







calculus derivatives continuity examples-counterexamples






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edited Dec 20 '18 at 2:13









Batominovski

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33.1k33293










asked Dec 20 '18 at 1:26









OneTwoOneOneTwoOne

307




307












  • $begingroup$
    You need to ensure that there are no points of inflection for $f$ in $(a, b) $ otherwise the result is false.
    $endgroup$
    – Paramanand Singh
    Dec 20 '18 at 7:00


















  • $begingroup$
    You need to ensure that there are no points of inflection for $f$ in $(a, b) $ otherwise the result is false.
    $endgroup$
    – Paramanand Singh
    Dec 20 '18 at 7:00
















$begingroup$
You need to ensure that there are no points of inflection for $f$ in $(a, b) $ otherwise the result is false.
$endgroup$
– Paramanand Singh
Dec 20 '18 at 7:00




$begingroup$
You need to ensure that there are no points of inflection for $f$ in $(a, b) $ otherwise the result is false.
$endgroup$
– Paramanand Singh
Dec 20 '18 at 7:00










1 Answer
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$begingroup$

No, not necessarily. Consider for example $f(x)=x^3$. Then $f'(0)=0$, but there are no $a$ and $b$ such that
$$frac{a^3-b^3}{a-b}=0$$
without having $a=b$.






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    1 Answer
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    8












    $begingroup$

    No, not necessarily. Consider for example $f(x)=x^3$. Then $f'(0)=0$, but there are no $a$ and $b$ such that
    $$frac{a^3-b^3}{a-b}=0$$
    without having $a=b$.






    share|cite|improve this answer









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      8












      $begingroup$

      No, not necessarily. Consider for example $f(x)=x^3$. Then $f'(0)=0$, but there are no $a$ and $b$ such that
      $$frac{a^3-b^3}{a-b}=0$$
      without having $a=b$.






      share|cite|improve this answer









      $endgroup$
















        8












        8








        8





        $begingroup$

        No, not necessarily. Consider for example $f(x)=x^3$. Then $f'(0)=0$, but there are no $a$ and $b$ such that
        $$frac{a^3-b^3}{a-b}=0$$
        without having $a=b$.






        share|cite|improve this answer









        $endgroup$



        No, not necessarily. Consider for example $f(x)=x^3$. Then $f'(0)=0$, but there are no $a$ and $b$ such that
        $$frac{a^3-b^3}{a-b}=0$$
        without having $a=b$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 20 '18 at 1:35









        user628021user628021

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