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I am just wondering, is it true that

$$6 \sqrt{-3 t (1+t)+\sqrt{4+12 t\ \ }\ \ }$$

$$\le\left(\frac{3 t (1+t)+\sqrt{4+12 t}}{1+t+t^2}\ \ \right)^{3/2}+4\sqrt{2}(1-t)^{3/2}$$

for all $\displaystyle t\in[0,1]$?

Thanks!

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11  
Oh, just what I was wondering too! :) –  Hans Lundmark Oct 19 '11 at 6:27
4  
(What I mean is that it might be helpful to provide some context. Is there any reason to believe it to be true?) –  Hans Lundmark Oct 19 '11 at 6:27
    
Since both sides are positive, you can square each side and eliminate some of the roots... and then if you keep squaring it the right way, you can reduce the problem to a polynomial inequality...Which may or may not be easy, but will probably be easier than this. –  N. S. Oct 19 '11 at 16:54
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1 Answer 1

I did not mess around with the function yet. Do you need a formal proof or what is your purpose for this inequality? A simple Mathematica plot shows that the inequality is most likely true:

enter image description here

Also Mathematica can show your inequality is true:

Reduce[a[t] <= b[t] && 0 <= t <= 1,t]

returns

0 <= t <= 1
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Yes, I need a formal proof. –  162 Oct 19 '11 at 7:06
    
So I guess this is homework, then you should tag it as homework. If it is not Mathematica is generally accepted as a formal proof if you don't use numerical functions. –  Listing Oct 19 '11 at 7:14
1  
Just curious - in what context did this problem arise? This is a difficult inequality to ponder just for the heck of it. If the result has some motiviation, it is easier to get enthusiastic. –  Chris Leary Oct 19 '11 at 17:09
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