Cyclic to symmetric conversion
by MathPassionForever, Sep 4, 2019, 7:54 AM
A comparatively much smaller post (as of now), as I don't have much information on this as of now.
We can clearly see that the SD theorems are strong. But then, some inequalities are cyclic, sigh. So the basic objective of this post is to serve as a collection of inequalities which can make cyclic inequalities symmetric (and these results need to be strong themselves,for our inequality shouldn't become false after their use
)
Here is the first one:

Proof: This inequality is obviously cyclic. So we may work with just 2 cases:
and 
In either case, we have:

Luckily, I have a question to post
Question: For nonnegative reals
, prove that

Solution
And in case someone doesn't find it that sharp, we have the famous and super strong Vasc inequality here!
I shall take leave here. Bye, see you soon!
We can clearly see that the SD theorems are strong. But then, some inequalities are cyclic, sigh. So the basic objective of this post is to serve as a collection of inequalities which can make cyclic inequalities symmetric (and these results need to be strong themselves,for our inequality shouldn't become false after their use

Here is the first one:

Proof: This inequality is obviously cyclic. So we may work with just 2 cases:


In either case, we have:

Luckily, I have a question to post

Question: For nonnegative reals


Solution
Of course do the substitution, and now we have:
Well well, looks ugly. But what is the SD for? The first check is
and the second one is
.
The first one becomes equivalent to (after multiplying a 27)
Looking at the huge coefficient of
, I think we're done. But the other one?
And I hope you saw this coming. The calculation is your job
Chill, will add that as well, but later.
![\[ (a^2 + b^2 + c^2)^2 \geq (\sqrt{2}-1)(a+b+c)(\sqrt{2}\left(a^3+b^3+c^3)+\dfrac{4}{27}(a+b+c)^3\right)\]](http://latex.artofproblemsolving.com/e/d/1/ed1caa4cef3ce1702be9fe4c4f33e485135ec567.png)


The first one becomes equivalent to (after multiplying a 27)

Looking at the huge coefficient of

And I hope you saw this coming. The calculation is your job

Chill, will add that as well, but later.
And in case someone doesn't find it that sharp, we have the famous and super strong Vasc inequality here!
![\[ (a^2 + b^2 + c^2)^2 \geq 3(a^3b + b^3c + c^3a) \ \forall a,b,c \in \mathbb{R} \]](http://latex.artofproblemsolving.com/7/4/6/74654a43f2ccd3f8db453256b7b230baa274c910.png)
This post has been edited 5 times. Last edited by MathPassionForever, Sep 5, 2019, 8:32 PM