Find the inverse, if possible

Question

A=[5 -4]

    [-1 1]

(the brackets are actually suppose to be conjoined together)

1st row=? 2nd row=?

Answer 1

A^-1=1/1 [1 4]

            [1 5]

 

For two x two matrix, swap the diagonal elements and reverse the sign of the other two elements.  Divide each element of the inverse by the determinant of the original matrix.