Posted by haifeng on 2019-01-13 19:59:58 last update 2019-01-13 19:59:58 | Answers (1) | 收藏
设 $A,B$ 是 $n$ 阶实方阵, 且满足 $\mathrm{rank}(A+B)=n$, 证明: $A^T A+B^T B$ 是正定矩阵.