y=(2x²-2x+2+1)/(x²-x+1)=(2x²-2x+2)/(x²-x+1)+1/(x²-x+1)=2+1/(x²-x+1)x²-x+1=(x-1/2)²+3/4>=3/4所以0<1/(x²-x+1)<=4/32<2+1/(x²-x+1)<=10/3值域(2,10/3]
