已知矩阵A和B满足关系式AB=A+2B,其中A=4 2 3,求B 1 1 0 -1 2 3

如题所述

第1个回答  2011-05-13
因为 AB=A+2B
所以 (A-2E)B = A

(A-2E,A) =
4 2 3 1 0 0
1 1 0 0 1 0
-1 2 3 0 0 1

r1-4r2, r3+r2
0 -2 3 1 -4 0
1 1 0 0 1 0
0 3 3 0 1 1

r3*(1/3), r1+2r3, r2-r3
0 0 5 1 -10/3 2/3
1 0 -1 0 2/3 -1/3
0 1 1 0 1/3 1/3

r1*(1/5), r2+r1, r3-r1
0 0 1 1/5 -2/3 2/15
1 0 0 1/5 0 -1/5
0 1 0 -1/5 1 1/5

交换行
1 0 0 1/5 0 -1/5
0 1 0 -1/5 1 1/5
0 0 1 1/5 -2/3 2/15

X =
1/5 0 -1/5
-1/5 1 1/5
1/5 -2/3 2/15

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第2个回答  2011-05-14
AB=A+2B
AB-2B=A
(A-2E)B=A
B=inv(A-2E)*A
matlab语句如下:
>> A=[4,2,3;1,1,0;-1,2,3];
>> B=inv(A-2*eye(size(A)))*A;
B =

3.0000 -8.0000 -6.0000
2.0000 -9.0000 -6.0000
-2.0000 12.0000 9.0000