a^2+b^2-6ab=0
a^2+2ab+b^2=8ab,(a+b)^2=8ab,a+b=√(8ab)
a^2-2ab+b^2=4ab,(a-b)^2=4ab,a-b=√(4ab),b-a=-√(4ab)
(a+b)/(b-a)=√(8ab)/-√(4ab)=-√2