设k1(a1+a2)+k2(a2+a3)+k3(a3+a4)+k4(a4-a1)=0整理后 得到(k1-k4)a1+(k1+k2)a2+(k2+k3)a3+(k3+k4)a4=0由于a1,a2,a3,a4 线性无关,则k1-k4=k1+k2=k2+k3=k3+k4=0解得k1=k2=k3=k4=0所以a1+a2,a2+a3,a3+a4,a4-a1线性无关...