设初项为a1,公比为q,则有S5=a1(1-q的5次方)/(1-q),a2+a3+a4+a5+a6=S6-a1=a1(1-q的6次方)/(1-q)-a1=a1q(1-q的5次方)/(1-q),S5/(a2+a3+a4+a5+a6)=1/q=93/186=1/2,所以q=2,a1=3,所以a8=a1q的7次方=384...