Processing math: 100%

kuing群里天书问的一个不等式

陈洪葛 posted @ 12 年前 in 不等式 , 1310 阅读

Let a,b,c>0,with a+b+c=3,Prove that
a3a2+3b2+b3b2+3c2+c3c2+3a232

Proof:
cyca3a2+3b2=6cyca24a(a+b+c)3(a2+3b2)12cyca24a(a+b+c)+3(a2+3b2)=12cyca27a2+9b2+4ab+4ca
Now,Using the Awesome CYH technology,we have
(cyca27a2+9b2+4ab+4ca)[cyc(2a+c)2(7a2+9b2+4ab+4ca)][cyca(c+2a)]2=(2cyca2+cycab)2
Thus,it's suffice to check
8(2cyca2+cycab)2cyc(2a+c)2(7a2+9b2+4ab+4ca)
Or
cyca4+cyca2b2+3cyca3b3cycab32abccyca0
Which is not a problem for us now,so we are done!


登录 *


loading captcha image...
(输入验证码)
or Ctrl+Enter