2181 21-58 1-39-6 1-309 D2= D 02-52 4 02-1-5 1406 4-70 -27 =27 D,81 x1= =3, x2=2。-108 D27 D27 x3=D2=-27=-1,x,=Dn=27=1 上或1 4 0 6 0 2 5 2 1 3 9 6 2 1 8 1 3 − − − D = = −27, 1 4 7 0 0 2 1 5 1 3 0 9 2 1 5 8 4 − − − − − D = = 27, 3, 27 81 1  1 = = = D D x 4, 27 108 2 2 = − − = = D D x 1, 27 27 3 3 = − − = = D D x 1. 27 4 27 4 = = = D D x