2x-1>=0
x>=1/2
y=x+√2x-1
y>=1/2
y^2-3xy+x^2=2x-1
x^2-(3y+2)x+y^2+1=0
(3y+2)^2-4(y^2+1)>=0
9y^2+12y+4-4y^2-4>=0
5y^2+12y>=0
y(5y+12)>=0
y>=0或y<=-12/5
综述Y>=1/2