(a/(ab-b^2)-b/(a^2-ab))/((1+a^2+b^2)/2ab)=(a/(b*(a-b))-b/(a*(a-b)))/((1+a^2+b^2)/2ab)=((a^2-b^2)/(a*b*(a-b)))/((1+a^2+b^2)/2ab)=((a+b)/(a*b))/((1+a^2+b^2)/2ab)=(2*(a+b))/(1+a^2+b^2)
a=-1+根号3,b=-1-根号3.
a+b=(-1+根号3)+(-1-根号3)=-2
a^2+b^2=(-1+根号3)^2+(-1-根号3)^2=(1-2*根号3+3)+(1+2*根号3+3)=8
代入上式得
(2*(a+b))/(1+a^2+b^2)=(2×(-2))/(1+8)=-4/9