ĐK: `0<x,y<1`
`P=(1-y)/\sqrt{y}+(1-x)/\sqrt{x}`
`P=(1/\sqrt{x}+1/\sqrt{y})-(\sqrt{x}+\sqrt{y})`
`P>= 2. \sqrt{1/\sqrt{xy}} -(x+1/2+y+1/2)/\sqrt{2}`
`P>=2. \sqrt{1/((x+y)/2)}-2/\sqrt{2}`
`P>=2\sqrt{2}-\sqrt{2}=\sqrt{2}`
Dấu = xảy ra khi `x=y=1/2`
Vậy `P_(min)=\sqrt{2}<=>x=y=1/2`