设矩阵A=
(1-12
-2-1-2
433)，
则A-1=_____．
【正确答案】：(3 9 4 -2 -5 -2 -2 -7 -3) 解析：(A，E)= (1 -1 2 1 0 0 -2 -1 -2 0 1 0 4 3 3 0 0 1) → (1 -1 2 1 0 0 0 -3 2 2 1 0 0 1 -1 0 2 1) → (1 0 1 1 2 1 0 1 -1 0 2 1 0 0 -1 2 7 3) → (1 0 0 3 9 4 0 1 0 -2 -5 -2 0 0 1 -2 -7 -3) =(E，A-1)．
