Question 788950
A=[[1  2] [ -4 4]]

inv(A)= [[1/3  -1/6] [ 1/3  1/12]]


[[x] [y]] = 
inv(A) [[6] [24]] =
[[1/3  -1/6] [ 1/3  1/12][[6] [24]] =
[[-2] [4]]