Matrix

a) Find the inverse of A by letting
...........( a b c )............(-1 1 2)

A^-1 =( d e f ) , if A = (3 -1 1)

..........( g h h )............(-1 3 4)
b) Solve the following set of equations using the following methods:
-Y1 + Y2 + 2 Y3 = 2
3 Y1- Y2 + Y3 = 6
- Y1+ 3 Y2 + 4 Y3 = 4
i)Determinant Method; and
ii)Matrix Method.
c)Find the co-factors and the determinant of matrix
.......( 2 , 0 ,-4 , 6)
.......(4 ,5 ,1 , 0)
D= .(0 ,2 , 6 ,-1)
.......(-3 ,8 ,9 , 1)