How do I prove the following inequality? [duplicate]

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  • Prove that $fracb^2+c^2b+c+fracc^2+a^2c+a+fraca^2+b^2a+b ge a+b+c$

    3 answers



How do I proceed to solve the inequality
$$frac(a^2+b^2)(a+b) + frac (b^2+c^2)(b+c) + frac(a^2+c^2)(a+c) geq (a+b+c)$$ where $a , b , c > 0$

I have thought of taking the terms on the $LHS$ and converting them to $AM$ and then use the $AM-GM$ theorem , but I cant figure out how to convert $frac (a^2+b^2)(a+b)$ to $AM$.
I have tried finding $a_1$ and $a_2$ by doing
$ (frac(a_1+a_2)2bigr)^2 geq$ $frac(a^2+b^2)(a+b)$







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marked as duplicate by Martin R, José Carlos Santos, abiessu, Ethan Bolker, Parcly Taxel Jul 19 at 1:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.










  • 2




    Are the $a,b,c$ positive reals?
    – Dr. Sonnhard Graubner
    Jul 18 at 17:20










  • Yes , I am really sorry I forgot to mention that.
    – mampuuu
    Jul 18 at 17:32














up vote
1
down vote

favorite













This question already has an answer here:



  • Prove that $fracb^2+c^2b+c+fracc^2+a^2c+a+fraca^2+b^2a+b ge a+b+c$

    3 answers



How do I proceed to solve the inequality
$$frac(a^2+b^2)(a+b) + frac (b^2+c^2)(b+c) + frac(a^2+c^2)(a+c) geq (a+b+c)$$ where $a , b , c > 0$

I have thought of taking the terms on the $LHS$ and converting them to $AM$ and then use the $AM-GM$ theorem , but I cant figure out how to convert $frac (a^2+b^2)(a+b)$ to $AM$.
I have tried finding $a_1$ and $a_2$ by doing
$ (frac(a_1+a_2)2bigr)^2 geq$ $frac(a^2+b^2)(a+b)$







share|cite|improve this question













marked as duplicate by Martin R, José Carlos Santos, abiessu, Ethan Bolker, Parcly Taxel Jul 19 at 1:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.










  • 2




    Are the $a,b,c$ positive reals?
    – Dr. Sonnhard Graubner
    Jul 18 at 17:20










  • Yes , I am really sorry I forgot to mention that.
    – mampuuu
    Jul 18 at 17:32












up vote
1
down vote

favorite









up vote
1
down vote

favorite












This question already has an answer here:



  • Prove that $fracb^2+c^2b+c+fracc^2+a^2c+a+fraca^2+b^2a+b ge a+b+c$

    3 answers



How do I proceed to solve the inequality
$$frac(a^2+b^2)(a+b) + frac (b^2+c^2)(b+c) + frac(a^2+c^2)(a+c) geq (a+b+c)$$ where $a , b , c > 0$

I have thought of taking the terms on the $LHS$ and converting them to $AM$ and then use the $AM-GM$ theorem , but I cant figure out how to convert $frac (a^2+b^2)(a+b)$ to $AM$.
I have tried finding $a_1$ and $a_2$ by doing
$ (frac(a_1+a_2)2bigr)^2 geq$ $frac(a^2+b^2)(a+b)$







share|cite|improve this question














This question already has an answer here:



  • Prove that $fracb^2+c^2b+c+fracc^2+a^2c+a+fraca^2+b^2a+b ge a+b+c$

    3 answers



How do I proceed to solve the inequality
$$frac(a^2+b^2)(a+b) + frac (b^2+c^2)(b+c) + frac(a^2+c^2)(a+c) geq (a+b+c)$$ where $a , b , c > 0$

I have thought of taking the terms on the $LHS$ and converting them to $AM$ and then use the $AM-GM$ theorem , but I cant figure out how to convert $frac (a^2+b^2)(a+b)$ to $AM$.
I have tried finding $a_1$ and $a_2$ by doing
$ (frac(a_1+a_2)2bigr)^2 geq$ $frac(a^2+b^2)(a+b)$





This question already has an answer here:



  • Prove that $fracb^2+c^2b+c+fracc^2+a^2c+a+fraca^2+b^2a+b ge a+b+c$

    3 answers









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share|cite|improve this question




share|cite|improve this question








edited Jul 18 at 17:33
























asked Jul 18 at 17:07









mampuuu

304




304




marked as duplicate by Martin R, José Carlos Santos, abiessu, Ethan Bolker, Parcly Taxel Jul 19 at 1:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.






marked as duplicate by Martin R, José Carlos Santos, abiessu, Ethan Bolker, Parcly Taxel Jul 19 at 1:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.









  • 2




    Are the $a,b,c$ positive reals?
    – Dr. Sonnhard Graubner
    Jul 18 at 17:20










  • Yes , I am really sorry I forgot to mention that.
    – mampuuu
    Jul 18 at 17:32












  • 2




    Are the $a,b,c$ positive reals?
    – Dr. Sonnhard Graubner
    Jul 18 at 17:20










  • Yes , I am really sorry I forgot to mention that.
    – mampuuu
    Jul 18 at 17:32







2




2




Are the $a,b,c$ positive reals?
– Dr. Sonnhard Graubner
Jul 18 at 17:20




Are the $a,b,c$ positive reals?
– Dr. Sonnhard Graubner
Jul 18 at 17:20












Yes , I am really sorry I forgot to mention that.
– mampuuu
Jul 18 at 17:32




Yes , I am really sorry I forgot to mention that.
– mampuuu
Jul 18 at 17:32










2 Answers
2






active

oldest

votes

















up vote
1
down vote



accepted










If $a$, $b$, $c>0$ then
$$fraca^2+b^2a+bgefraca+b2$$
etc.






share|cite|improve this answer





















  • Sir , how did you get that identity?Is that $AM-GM$ inequality?
    – mampuuu
    Jul 18 at 17:35











  • I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
    – Lord Shark the Unknown
    Jul 18 at 17:37






  • 1




    @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
    – Math Lover
    Jul 18 at 17:41

















up vote
0
down vote













Using Cauchy Schwarz in Engel form, we have



$$!!fraca^2a+b+fracb^2b+c+fracc^2a+c+
fracb^2a+b+fracc^2b+c+fraca^2a+cgeq frac(a+b+c)^22(a+b+c)+frac(b+c+a)^22(a+b+c)= a+b+c$$






share|cite|improve this answer






























    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    1
    down vote



    accepted










    If $a$, $b$, $c>0$ then
    $$fraca^2+b^2a+bgefraca+b2$$
    etc.






    share|cite|improve this answer





















    • Sir , how did you get that identity?Is that $AM-GM$ inequality?
      – mampuuu
      Jul 18 at 17:35











    • I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
      – Lord Shark the Unknown
      Jul 18 at 17:37






    • 1




      @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
      – Math Lover
      Jul 18 at 17:41














    up vote
    1
    down vote



    accepted










    If $a$, $b$, $c>0$ then
    $$fraca^2+b^2a+bgefraca+b2$$
    etc.






    share|cite|improve this answer





















    • Sir , how did you get that identity?Is that $AM-GM$ inequality?
      – mampuuu
      Jul 18 at 17:35











    • I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
      – Lord Shark the Unknown
      Jul 18 at 17:37






    • 1




      @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
      – Math Lover
      Jul 18 at 17:41












    up vote
    1
    down vote



    accepted







    up vote
    1
    down vote



    accepted






    If $a$, $b$, $c>0$ then
    $$fraca^2+b^2a+bgefraca+b2$$
    etc.






    share|cite|improve this answer













    If $a$, $b$, $c>0$ then
    $$fraca^2+b^2a+bgefraca+b2$$
    etc.







    share|cite|improve this answer













    share|cite|improve this answer



    share|cite|improve this answer











    answered Jul 18 at 17:23









    Lord Shark the Unknown

    85.5k951112




    85.5k951112











    • Sir , how did you get that identity?Is that $AM-GM$ inequality?
      – mampuuu
      Jul 18 at 17:35











    • I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
      – Lord Shark the Unknown
      Jul 18 at 17:37






    • 1




      @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
      – Math Lover
      Jul 18 at 17:41
















    • Sir , how did you get that identity?Is that $AM-GM$ inequality?
      – mampuuu
      Jul 18 at 17:35











    • I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
      – Lord Shark the Unknown
      Jul 18 at 17:37






    • 1




      @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
      – Math Lover
      Jul 18 at 17:41















    Sir , how did you get that identity?Is that $AM-GM$ inequality?
    – mampuuu
    Jul 18 at 17:35





    Sir , how did you get that identity?Is that $AM-GM$ inequality?
    – mampuuu
    Jul 18 at 17:35













    I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
    – Lord Shark the Unknown
    Jul 18 at 17:37




    I don't think so, but it's related to Cauchy-Schwarz. It's quite easy to prove from scratch.
    – Lord Shark the Unknown
    Jul 18 at 17:37




    1




    1




    @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
    – Math Lover
    Jul 18 at 17:41




    @mampuuu This inequality is the quadratic-arithmetic mean inequality in disguise.
    – Math Lover
    Jul 18 at 17:41










    up vote
    0
    down vote













    Using Cauchy Schwarz in Engel form, we have



    $$!!fraca^2a+b+fracb^2b+c+fracc^2a+c+
    fracb^2a+b+fracc^2b+c+fraca^2a+cgeq frac(a+b+c)^22(a+b+c)+frac(b+c+a)^22(a+b+c)= a+b+c$$






    share|cite|improve this answer



























      up vote
      0
      down vote













      Using Cauchy Schwarz in Engel form, we have



      $$!!fraca^2a+b+fracb^2b+c+fracc^2a+c+
      fracb^2a+b+fracc^2b+c+fraca^2a+cgeq frac(a+b+c)^22(a+b+c)+frac(b+c+a)^22(a+b+c)= a+b+c$$






      share|cite|improve this answer

























        up vote
        0
        down vote










        up vote
        0
        down vote









        Using Cauchy Schwarz in Engel form, we have



        $$!!fraca^2a+b+fracb^2b+c+fracc^2a+c+
        fracb^2a+b+fracc^2b+c+fraca^2a+cgeq frac(a+b+c)^22(a+b+c)+frac(b+c+a)^22(a+b+c)= a+b+c$$






        share|cite|improve this answer















        Using Cauchy Schwarz in Engel form, we have



        $$!!fraca^2a+b+fracb^2b+c+fracc^2a+c+
        fracb^2a+b+fracc^2b+c+fraca^2a+cgeq frac(a+b+c)^22(a+b+c)+frac(b+c+a)^22(a+b+c)= a+b+c$$







        share|cite|improve this answer















        share|cite|improve this answer



        share|cite|improve this answer








        edited Jul 18 at 18:14









        Math Lover

        12.4k21232




        12.4k21232











        answered Jul 18 at 17:27









        Dr. Sonnhard Graubner

        66.8k32659




        66.8k32659












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