A Generalized Inequality

For discussing Olympiad Level Algebra (and Inequality) problems
User avatar
Sazid Akhter Turzo
Posts:69
Joined:Sat Feb 18, 2012 9:15 am
Location:Sirajganj
Contact:
A Generalized Inequality

Unread post by Sazid Akhter Turzo » Tue Jul 31, 2012 10:37 pm

Prove that...
the inequality $\sum_{sym}\frac{a}{\sqrt{a^2 + kbc}} \geq \frac{3}{\sqrt{1+k}}$
is true for all $a, b, c > 0$ $iff$ $k \geq 8$.

comment:
It's a generalized form of IMO SL-2001-A6 ;)

User avatar
Phlembac Adib Hasan
Posts:1016
Joined:Tue Nov 22, 2011 7:49 pm
Location:127.0.0.1
Contact:

Re: A Generalized Inequality

Unread post by Phlembac Adib Hasan » Tue Jul 31, 2012 10:49 pm

Solution(s):One huge solution was given in the Compendium.
Another one can be found using Holder.(Of course, this is my solution :P )
The third solution needs to use Jensen.
See this:
http://www.artofproblemsolving.com/Foru ... 38&t=17451
Welcome to BdMO Online Forum. Check out Forum Guides & Rules

Post Reply