求y=x+1/(x方+x+1)的值域

y=(x+1)/(x^2+x+1)易得分母不等于零,则定义域是R.y(x^2+x+1)=x+1yx^2+(y-1)x+y-1=0y=0时,x=-1.y不=0时,方程有解,则判别式>=0即(y-1)^2-4y(y-1)>=0(y-1)(y-1-4y)>=0(y-1)(-3y-1)>=0(y-1)(3y+1)...