①x^2=3x-1代入得(3x-1)/[(3x-1)²+(3x-1)+1]=(3x-1)/(9x²-3x+1)=(3x-1)/[9(3x-1)-(3x-1)]=1/8
②x+1/x=3,x²+1/x²=9-2=7
(x^2)/(x^4+x^2+1)=1/(x^4/x²+x^2/x²+1/x²)=1/(x²+1+1/x²)=1/(7+1)=1/8
①x^2=3x-1代入得(3x-1)/[(3x-1)²+(3x-1)+1]=(3x-1)/(9x²-3x+1)=(3x-1)/[9(3x-1)-(3x-1)]=1/8
②x+1/x=3,x²+1/x²=9-2=7
(x^2)/(x^4+x^2+1)=1/(x^4/x²+x^2/x²+1/x²)=1/(x²+1+1/x²)=1/(7+1)=1/8