\(P=\frac{\sqrt{x}}{\sqrt{xy}+\sqrt{x}+2}+\frac{\sqrt{y}}{\sqrt{yz}+\sqrt{y}+1}+\frac{2\sqrt{z}}{\sqrt{xz}+2\sqrt{x}+2}\)
\(=\frac{\sqrt{xz}}{\sqrt{xyz}+\sqrt{xz}+2\sqrt{z}}+\frac{\sqrt{xyz}}{\sqrt{xyz^2}+\sqrt{xyz}+\sqrt{xz}}+\frac{2\sqrt{x}}{\sqrt{xz}+2\sqrt{z}+2}\)
\(=\frac{\sqrt{xz}}{\sqrt{xz}+2\sqrt{x}+2}+\frac{2}{2\sqrt{x}+2+\sqrt{xz}}+\frac{2\sqrt{z}}{\sqrt{xz}+2\sqrt{z}+2}\) (do \(xyz=4\))
\(=\frac{\sqrt{xz}+2\sqrt{z}+2}{\sqrt{xz}+2\sqrt{z}+2}=1\)