■A的各阶顺序主子式均不为零,即 Ik A ≠0(k=1,2,n) k1 k◼ A的各阶顺序主子式均不为零，即 0 ( 1,2,... ) ... ... ... ... ... 1 1 1 1 k n a a a a A k kk k k =  =