Let A be an m x m matrix partitioned as A = rank (A) = rank (A11) = m. 1.2.1 Show that A22 = A21A A12. 1.2.2 Use the result of part 1.2.1 to show that B = A. A11 A12 A21 A22 (0) (0) (0) where A is m x m and (8) is a generalised inverse of (8)