2a12a22.a2n[A|=0a.2n2aiαr,其中 (0,ai2,,a'm)=α;i=2,..,nanla由[A|=0知,=0,aa22由归纳假设，矩阵的秩<n一1,a'n2q'83.4矩阵的秩A§3.4 矩阵的秩 11 12 1 22 2 2 0 0 n n n nn a a a a a A a a   =   22 2 11 2 n n nn a a a a a   =   1 2 1 11 (0, , , ) , 2, , i i in i a a a i n a 其中   = − =   由 A = 0 知， 22 2 2 0, n n nn a a a a   =   由归纳假设，矩阵 的秩＜n－1， 22 2 2 n n nn a a a a            