矩阵BTAB TAnB]的后k行为零行。 记 B=TB A= TAT U=TBAB…]=BAB…“ B, B=TB= A= TAT- TAB- TAT-TB=4B 0 A B A AB= AB/→AB1=0 A2B=AAB A A24B1 AB 0 0 A AB →A341B1=0矩阵 TB TAB TA B  n−1 的后 k行为零行。 记 1 , − B = TB A = TAT     0 0 3 1 3 1 1 1 3 4 1 21 1 1 1 1  =   =   = = = =   = = = =− − − − A B A B A B AB A A A A A A TAT TAB TAT TB A B B B TB U T B AB A B B A B A B  n  n 0 0 0 3 1 1 3 1 1 1 2 1 1 1 3 4 2 1 2  =  =  =   = = A A B A A B A B A B A A A A A B AAB