Compute (AB)-1 when A = and B-1 -= .

We have,

To find: (AB)-1


We know that,


(AB)-1 = B-1A-1


and here, B-1 is given but we have to find A-1 and


Firstly, we find |A|


Expanding |A| along C1, we get




= 1(8 – 6) – 0 + 3(-3 – 4)


= 1(2) + 3(-7)


= 2 – 21


= -19


Now, we have to find adj A and for that we have to find co-factors:













Now, we have



So,





Ans.


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