问题
解答题
设x,y,z∈R+,求证:
|
答案
设S=x+y+z
+x y+z
+y x+z z x+y
=
+S y+z
+S x+z
-3S x+y
≥
-39
+y+z S
+x+z S x+y S
=
-3=9 2 3 2
∴原不等式成立.
设x,y,z∈R+,求证:
|
设S=x+y+z
+x y+z
+y x+z z x+y
=
+S y+z
+S x+z
-3S x+y
≥
-39
+y+z S
+x+z S x+y S
=
-3=9 2 3 2
∴原不等式成立.