題組內容
2 Let $A, B \in M_{n \times n}(\mathbb{R})$.
a. (10) Show that \( \operatorname{rank}(AB) \leqslant \operatorname{rank}(B) \) and \( \operatorname{rank}(AB) \leqslant \operatorname{rank}(A) \).
2 Let $A, B \in M_{n \times n}(\mathbb{R})$.
a. (10) Show that \( \operatorname{rank}(AB) \leqslant \operatorname{rank}(B) \) and \( \operatorname{rank}(AB) \leqslant \operatorname{rank}(A) \).