Convex function exercise [on hold]












-1














having a bit of trouble with this exercise;



Let f be a function, convex on $mathbb{I}$, by writing $sum_{k=1}^{n}x_klambda_k $ for $ n ge 3 $ under the form $x_nlambda_n+(1-lambda_n)y_n$ with $y_n$ expressed with $x_k, kin [|1,n|] $ and $ lambda_q, qin[|1,n|]$ and $lambda_iin]0,1[$and $sum_{n}^{i=1}lambda_i = 1$ .
Prove that :
$sum_{k=1}^{n}lambda_kf(x_k)ge f(sum_{k=1}^{n}x_klambda_k)$.



The previous question was to demonstrate that ;
$zin ]x,y[ <=> existslambda, z=xlambda + (1-lambda)y$










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put on hold as off-topic by amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin yesterday


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." – amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin

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













  • May be n dimensional Jensen's inequality may fit the bill?
    – Satish Ramanathan
    2 days ago






  • 1




    This needs rewriting. It is strangely confusing.
    – zhw.
    2 days ago
















-1














having a bit of trouble with this exercise;



Let f be a function, convex on $mathbb{I}$, by writing $sum_{k=1}^{n}x_klambda_k $ for $ n ge 3 $ under the form $x_nlambda_n+(1-lambda_n)y_n$ with $y_n$ expressed with $x_k, kin [|1,n|] $ and $ lambda_q, qin[|1,n|]$ and $lambda_iin]0,1[$and $sum_{n}^{i=1}lambda_i = 1$ .
Prove that :
$sum_{k=1}^{n}lambda_kf(x_k)ge f(sum_{k=1}^{n}x_klambda_k)$.



The previous question was to demonstrate that ;
$zin ]x,y[ <=> existslambda, z=xlambda + (1-lambda)y$










share|cite|improve this question













put on hold as off-topic by amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin yesterday


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." – amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin

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













  • May be n dimensional Jensen's inequality may fit the bill?
    – Satish Ramanathan
    2 days ago






  • 1




    This needs rewriting. It is strangely confusing.
    – zhw.
    2 days ago














-1












-1








-1







having a bit of trouble with this exercise;



Let f be a function, convex on $mathbb{I}$, by writing $sum_{k=1}^{n}x_klambda_k $ for $ n ge 3 $ under the form $x_nlambda_n+(1-lambda_n)y_n$ with $y_n$ expressed with $x_k, kin [|1,n|] $ and $ lambda_q, qin[|1,n|]$ and $lambda_iin]0,1[$and $sum_{n}^{i=1}lambda_i = 1$ .
Prove that :
$sum_{k=1}^{n}lambda_kf(x_k)ge f(sum_{k=1}^{n}x_klambda_k)$.



The previous question was to demonstrate that ;
$zin ]x,y[ <=> existslambda, z=xlambda + (1-lambda)y$










share|cite|improve this question













having a bit of trouble with this exercise;



Let f be a function, convex on $mathbb{I}$, by writing $sum_{k=1}^{n}x_klambda_k $ for $ n ge 3 $ under the form $x_nlambda_n+(1-lambda_n)y_n$ with $y_n$ expressed with $x_k, kin [|1,n|] $ and $ lambda_q, qin[|1,n|]$ and $lambda_iin]0,1[$and $sum_{n}^{i=1}lambda_i = 1$ .
Prove that :
$sum_{k=1}^{n}lambda_kf(x_k)ge f(sum_{k=1}^{n}x_klambda_k)$.



The previous question was to demonstrate that ;
$zin ]x,y[ <=> existslambda, z=xlambda + (1-lambda)y$







convex-analysis






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share|cite|improve this question











share|cite|improve this question




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asked 2 days ago









user310148

22




22




put on hold as off-topic by amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin yesterday


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." – amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin

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 amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin yesterday


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." – amWhy, Paul Frost, Eevee Trainer, Saad, Lord_Farin

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












  • May be n dimensional Jensen's inequality may fit the bill?
    – Satish Ramanathan
    2 days ago






  • 1




    This needs rewriting. It is strangely confusing.
    – zhw.
    2 days ago


















  • May be n dimensional Jensen's inequality may fit the bill?
    – Satish Ramanathan
    2 days ago






  • 1




    This needs rewriting. It is strangely confusing.
    – zhw.
    2 days ago
















May be n dimensional Jensen's inequality may fit the bill?
– Satish Ramanathan
2 days ago




May be n dimensional Jensen's inequality may fit the bill?
– Satish Ramanathan
2 days ago




1




1




This needs rewriting. It is strangely confusing.
– zhw.
2 days ago




This needs rewriting. It is strangely confusing.
– zhw.
2 days ago










1 Answer
1






active

oldest

votes


















2














hint



$$sum_{i=1}^nlambda_ix_i=$$



$$lambda_nx_n+(1-lambda_n)sum_{i=1}^{n-1}frac{lambda_i x_i}{1-lambda_n}=$$



$$lambda_nx_n+(1-lambda_n)y_n$$






share|cite|improve this answer





















  • Hey thanks yea, sorry i forgot to say i got that part already sorry
    – user310148
    2 days ago


















1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









2














hint



$$sum_{i=1}^nlambda_ix_i=$$



$$lambda_nx_n+(1-lambda_n)sum_{i=1}^{n-1}frac{lambda_i x_i}{1-lambda_n}=$$



$$lambda_nx_n+(1-lambda_n)y_n$$






share|cite|improve this answer





















  • Hey thanks yea, sorry i forgot to say i got that part already sorry
    – user310148
    2 days ago
















2














hint



$$sum_{i=1}^nlambda_ix_i=$$



$$lambda_nx_n+(1-lambda_n)sum_{i=1}^{n-1}frac{lambda_i x_i}{1-lambda_n}=$$



$$lambda_nx_n+(1-lambda_n)y_n$$






share|cite|improve this answer





















  • Hey thanks yea, sorry i forgot to say i got that part already sorry
    – user310148
    2 days ago














2












2








2






hint



$$sum_{i=1}^nlambda_ix_i=$$



$$lambda_nx_n+(1-lambda_n)sum_{i=1}^{n-1}frac{lambda_i x_i}{1-lambda_n}=$$



$$lambda_nx_n+(1-lambda_n)y_n$$






share|cite|improve this answer












hint



$$sum_{i=1}^nlambda_ix_i=$$



$$lambda_nx_n+(1-lambda_n)sum_{i=1}^{n-1}frac{lambda_i x_i}{1-lambda_n}=$$



$$lambda_nx_n+(1-lambda_n)y_n$$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered 2 days ago









hamam_Abdallah

37.9k21634




37.9k21634












  • Hey thanks yea, sorry i forgot to say i got that part already sorry
    – user310148
    2 days ago


















  • Hey thanks yea, sorry i forgot to say i got that part already sorry
    – user310148
    2 days ago
















Hey thanks yea, sorry i forgot to say i got that part already sorry
– user310148
2 days ago




Hey thanks yea, sorry i forgot to say i got that part already sorry
– user310148
2 days ago



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