y=x+根号里x^2-3x+2
√（x^2-3x+2)=y-x
x^2-3x+2=y^2+x^2-2yx
(2y-3)x=y^2-2
x=(y^2-2)/(2y-3)
所以,2y-3≠0,y≠3/2
即：值域:y≠3/2