Let `A = ([-1,2],[1,-4]).` Then `A^(-1)` is .......................
`([1,-2], [1/2,1/2])`
`([-2,-1], [1/2, -1/2])`
`([-1/2, -1/2], [2, 1])`
`([-2, -1], [-1/2, -1/2])`
how does we get this ans?