求解矩阵方程XA=B其中,A=(5 3 1,1 -1 -2,-5 2 1),B=(-8 7 0,-5 19 0,-2 31 0).(注:A、B均为3*3矩阵)
求解矩阵方程XA=B
其中,A=(5 3 1,1 -1 -2,-5 2 1),B=(-8 7 0,-5 19 0,-2 31 0).(注:A、B均为3*3矩阵)
解: (I-A,B) = 0 -1 -3 2 5-2 -2 -7 0 1-3 -4 -8 -3 0r2-r3 0 -1 -3 2 5 1 2 1 3 1-3 -4 -8 -3 0r3+3r2 0 -1 -3 2 5 1 2 1 3 1 0 2 -5 6 3r2+2r1,r3+2r1 0 -1 -3 2 5 1 0 -5 7 11 0 0 -11 10 13r1*(-1),r3*(-1/11),r1r2 1 0 -5 7 11 0 1 3 -2 -5 0 0 1 -10/11 -13/11r1+5r3,r2-3r31 0 0 27/11 56/11 0 1 0 8/11 -16/11 0 0 1 -10/11 -13/11(I-A)^-1B = 27/11 56/11 8/11 -16/11-10/11 -13/11
X=1/D×A*B
D为矩阵A对应行列式的值,A*为矩阵A的伴随矩阵
(A^T,B^T)=
5 1 -5 -8 -5 -2
3 -1 2 7 19 31
1 -2 1 0 0 0
r1-5r3,r2-3r3
0 11 -10 -8 -5 -2
0 5 -1 7 19 31
1 -2 1 0 0 0
r1-2r2
0 1 -8 -22 -43 -64
0 5 -1 7 19 31
1 -2 1 0 0 0
r2-5r1,r3+2r1
0 1 -8 -22 -43 -64
0 0 39 117 234 351
1 0 -15 -44 -86 -128
r2*(1/39),r1+8r2,r3+15r2
1 0 0 1 4 7
0 1 0 2 5 8
0 0 1 3 6 9
所以 X =
1 2 3
4 5 6
7 8 9