x^2-2x+3=2yx-3y
x^2-(2+2y)x+(3+3y)=0
判別式：
4(y+1)^2-12(y+1)≥0
4(y+1)(y-2)≥0
y≥2或y≤-1函數y=（1+√x）/（1-√x）的值域是1+√x=y-y√x
(1+y)√x=(y-1)
√x=(y-1)/(y+1)
因為√x≥0
(y-1)/(y+1)≥0
(y-1)(y+1)≥0(y≠-1)
y≥1,或y<-1