48-日-4 4=8 0 -2 -1 -2 0 1 2 1 故 AB= 2 4 3 1 -1 1         − =       − −        − = 1 1 4 5 1 2 2 1 1 1 1 2 因A2 1B1 2         =       − +       −        − + = 0 3 1 1 1 2 1 1 1 2 A2 1B1 3 B2 3               − − − − = 1 1 1 0 2 4 5 3 0 1 2 1 0 2 1 2 故 AB