Math Forum :: View topic – Cyclic Inequality

Author Message

koopa

Frequent VisitorJoined: 21 Jan 2004Posts: 56

Posted: Thu Oct 28, 2004 11:32 am    Post subject: Cyclic Inequality

Suppose, a, b, c, d > 0 Prove that: a^4*b + b^4*c + c^4*d + d^4*a >= abcd(a + b + c + d).

Please help.

Ellen

Frequent VisitorJoined: 28 Oct 2003Posts: 197

Location: CUHK

Posted: Thu Oct 28, 2004 11:10 pm    Post subject:

A stupid way: By AM-GM,

Similarly,

Adding these and dividing both sides by 51 gives the result.

There maybe a nicer solution though…….

koopa

Frequent VisitorJoined: 21 Jan 2004Posts: 56

Posted: Fri Oct 29, 2004 1:35 am    Post subject:

Wow!!! That’s a brilliant solution.

All times are GMT + 8 Hours

 

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum