Question

设A为n阶实方阵,AT是A的转置矩阵,对于线性方程组Ⅰ:Ax=0和Ⅱ:AAT Ax=0,必有

Answer 1

选(A)

Ax=0 => AA^TAx=0 => x^TA^TAA^TAx=0 => (A^TAx)^T(A^TAx)=0 => A^TAx=0 => x^TA^TAx=0 => Ax=0