$f:[0,1]tomathbb{R}$ continuous, differentiable in $(0,1)$ such that $f(0)=0$ and $f(1)=1$ then...












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I don't have any idea of how to proceed. The complete problem is:



If $f:[0,1]tomathbb{R}$ is a continuous function in $[0,1]$ and differentiable in (0,1) such that $f(0)=0$ and $f(1)=1$. Prove that for all $kinmathbb{N}$ exist different $x_1,...,x_kin (0,1)$ such that $$sum_{i=1}^{k}frac{1}{f'(x_i)}=k$$



I'll be grateful for your help.










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put on hold as off-topic by user21820, José Carlos Santos, amWhy, Did, RRL Jan 7 at 17:34


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, José Carlos Santos, amWhy, Did, RRL

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    $begingroup$
    math.stackexchange.com/questions/366379/…
    $endgroup$
    – yuanming luo
    Jan 7 at 1:30
















-1












$begingroup$


I don't have any idea of how to proceed. The complete problem is:



If $f:[0,1]tomathbb{R}$ is a continuous function in $[0,1]$ and differentiable in (0,1) such that $f(0)=0$ and $f(1)=1$. Prove that for all $kinmathbb{N}$ exist different $x_1,...,x_kin (0,1)$ such that $$sum_{i=1}^{k}frac{1}{f'(x_i)}=k$$



I'll be grateful for your help.










share|cite|improve this question











$endgroup$



put on hold as off-topic by user21820, José Carlos Santos, amWhy, Did, RRL Jan 7 at 17:34


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, José Carlos Santos, amWhy, Did, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.









  • 2




    $begingroup$
    math.stackexchange.com/questions/366379/…
    $endgroup$
    – yuanming luo
    Jan 7 at 1:30














-1












-1








-1





$begingroup$


I don't have any idea of how to proceed. The complete problem is:



If $f:[0,1]tomathbb{R}$ is a continuous function in $[0,1]$ and differentiable in (0,1) such that $f(0)=0$ and $f(1)=1$. Prove that for all $kinmathbb{N}$ exist different $x_1,...,x_kin (0,1)$ such that $$sum_{i=1}^{k}frac{1}{f'(x_i)}=k$$



I'll be grateful for your help.










share|cite|improve this question











$endgroup$




I don't have any idea of how to proceed. The complete problem is:



If $f:[0,1]tomathbb{R}$ is a continuous function in $[0,1]$ and differentiable in (0,1) such that $f(0)=0$ and $f(1)=1$. Prove that for all $kinmathbb{N}$ exist different $x_1,...,x_kin (0,1)$ such that $$sum_{i=1}^{k}frac{1}{f'(x_i)}=k$$



I'll be grateful for your help.







calculus derivatives continuity






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edited Jan 7 at 1:11









Clayton

18.9k33085




18.9k33085










asked Jan 7 at 0:57









Raul_MFerRaul_MFer

453




453




put on hold as off-topic by user21820, José Carlos Santos, amWhy, Did, RRL Jan 7 at 17:34


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, José Carlos Santos, amWhy, Did, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.




put on hold as off-topic by user21820, José Carlos Santos, amWhy, Did, RRL Jan 7 at 17:34


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, José Carlos Santos, amWhy, Did, RRL

If this question can be reworded to fit the rules in the help center, please edit the question.








  • 2




    $begingroup$
    math.stackexchange.com/questions/366379/…
    $endgroup$
    – yuanming luo
    Jan 7 at 1:30














  • 2




    $begingroup$
    math.stackexchange.com/questions/366379/…
    $endgroup$
    – yuanming luo
    Jan 7 at 1:30








2




2




$begingroup$
math.stackexchange.com/questions/366379/…
$endgroup$
– yuanming luo
Jan 7 at 1:30




$begingroup$
math.stackexchange.com/questions/366379/…
$endgroup$
– yuanming luo
Jan 7 at 1:30










1 Answer
1






active

oldest

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$begingroup$

Hint: there are $t_0 = 0 < ldots < t_k = 1$ such that $f(t_j) = j/k$. Use the Mean Value Theorem in each interval $[t_{j-1}, t_j]$.






share|cite|improve this answer









$endgroup$




















    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    5












    $begingroup$

    Hint: there are $t_0 = 0 < ldots < t_k = 1$ such that $f(t_j) = j/k$. Use the Mean Value Theorem in each interval $[t_{j-1}, t_j]$.






    share|cite|improve this answer









    $endgroup$


















      5












      $begingroup$

      Hint: there are $t_0 = 0 < ldots < t_k = 1$ such that $f(t_j) = j/k$. Use the Mean Value Theorem in each interval $[t_{j-1}, t_j]$.






      share|cite|improve this answer









      $endgroup$
















        5












        5








        5





        $begingroup$

        Hint: there are $t_0 = 0 < ldots < t_k = 1$ such that $f(t_j) = j/k$. Use the Mean Value Theorem in each interval $[t_{j-1}, t_j]$.






        share|cite|improve this answer









        $endgroup$



        Hint: there are $t_0 = 0 < ldots < t_k = 1$ such that $f(t_j) = j/k$. Use the Mean Value Theorem in each interval $[t_{j-1}, t_j]$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 7 at 1:13









        Robert IsraelRobert Israel

        319k23208458




        319k23208458















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