即(4x²-4x+1)+(y²-6y+9)=0
(2x-1)²+(y-3)²=0
所以2x-1=y-3=0
x=1/2,y=3
原式=2x√x+√(xy)-x√x-5√(xy)
=x√x-4√(xy)
=√2/4-4√(3/2)
=√2/4-2√6