x-2>=0
2-x>=0
∴x=2
当x=2时
y＞根号x-2+根号2-x+2
∴y>2
2-y分之1乘根号y的平方-4y+4+根号2x
=√(y-2)²/(2-y)+√(2x)
=(y-2)/(2-y)+√4
=-1+2
=1