n dimensional row vector

By linking some slimple nature of the linear equation group and n dimension vector,derive out two pieces of special nature,and then prove several important theorems of the order about matrix succinctly by these two pieces of nature.

用线性方程组及n维向量的一些简单性质,推导出n维向量的两个特殊性质,再用这两个性质简捷地证明了有关矩阵的秩的几个重要定理。