Matriceshard
0:00.0

Sylvester's rank inequality states: For matrices ARm×nA \in \mathbb{R}^{m \times n} and BRn×pB \in \mathbb{R}^{n \times p},rank(A)+rank(B)nrank(AB)min(rank(A),rank(B))\text{rank}(A) + \text{rank}(B) - n \leq \text{rank}(AB) \leq \min(\text{rank}(A), \text{rank}(B))For A=(100100)A = \begin{pmatrix} 1 & 0 \\ 0 & 1 \\ 0 & 0 \end{pmatrix} (rank 2, dimensions 3×23 \times 2) and B=(100000)B = \begin{pmatrix} 1 & 0 & 0 \\ 0 & 0 & 0 \end{pmatrix} (rank 1, dimensions 2×32 \times 3), what must rank(AB)\text{rank}(AB) equal?