About Lesson
14.3 Proof of Inequalities 不等式的证明
Prove the following inequalities 证明以下不等式
(1)
>
, 
(1)



(2)
, x, y > 0



(3) >
,
(4) Prove that
,
Hence or otherwise, prove that (x + y + z)2
3 (xy + yz + xz)



Hence or otherwise, prove that (x + y + z)2

证明
,
据此或其他方法,证明 (x + y + z)2 3 (xy + yz + xz)