https://diendantoanhoc.net/topic/74052-cho-xyz0-xyz1-tim-gtnn-c%E1%BB%A7a-p-fracx2yzyzfracy2zxzxfracz2xyxy/
vào là có ok
Có \(3-P=\left(1-\frac{x}{x+1}\right)+\left(1-\frac{y}{y+1}\right)+\left(1-\frac{z}{z+1}\right)\)
\(=\frac{1}{x+1}+\frac{1}{y+1}+\frac{1}{z+1}\ge\frac{9}{\left(x+y+z\right)+3}\left(Svacxo\right)\)
\(=\frac{9}{2004+3}=\frac{9}{2007}\)
\(\Rightarrow3-P\ge\frac{9}{2007}\)
\(\Rightarrow P\le\frac{668}{223}\)
Dấu "=" tại x = y = z = 668