y=(x-1)/(x²+x+1)
x²y+xy+y-x+1=0
yx²+(y-1)x+y+1=0
x有解,即△≥0,即(y-1)²-4*y*(y+1)≥0
3y²+6y-1≤0
得-1-2√3/3≤y≤1+2√3/3
如果我对题目没有理解错的话...