3) $P^2=(\sqrt{1-x}+\sqrt{1-y}+\sqrt{1-z})^2\leq (1+1+1)(1-x+1-x+1-z)=3.(3-1)=6$$\Rightarrow P\leq \sqrt{6}$vậy $P_max=\sqrt{6}$ khi $x=y=z=\frac{1}{3}$
3)
P2=(√1−x+√1−y+√1−z)2≤(1+1+1)(1−x+1−x+1−z)=6 (bunhia)⇒P≤√6vậy $P_
{max
}=\sqrt{6}
khix=y=z=\frac{1}{3}$