x/(x²-x+1)=2分子分母同时处以x得1/(x-1+1/x)=2x+1/x=3/2x²/(x^4+x²+1)分子分母同时处以x²得=1/[x²+1+1/x²]=1/[(x+1/x)²-2+1]=1/[(x+1/x)²-1]=1/[9/4-1]=4/5...