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.