Question

设A=|4 2 3 ,1 1 0,-1 2 3 |,且矩阵X满足AX=A+2X,求X

Answer 1

由 AX=A+2X 得 (A-2E)X = A.
(A-2E,A) =
2 2 3 4 2 3
1 -1 0 1 1 0
-1 2 1 -1 2 3
r1-2r2,r3+r2
0 4 3 2 0 3
1 -1 0 1 1 0
0 1 1 0 3 3
r1-4r3,r2+r3
0 0 -1 2 -12 -9
1 0 1 1 4 3
0 1 1 0 3 3
r2+r1,r3+r1,r1*(-1)
0 0 1 -2 12 9
1 0 0 3 -8 -6
0 1 0 2 -9 -6
交换行
1 0 0 3 -8 -6
0 1 0 2 -9 -6
0 0 1 -2 12 9
X =
3 -8 -6
2 -9 -6
-2 12 9