If , find A – 1 and hence solve the system of linear equations:2 x – 3 y + 5z = 11, 3x + 2y – 4z = – 5, x + y – 2z = – 3
A =
|A| = 2(0) + 3(– 2) + 5(1)
= – 1
Now, the cofactors of A
C11 = (– 1)1 + 1 – 4 + 4 = 0
C21 = (– 1)2 + 1 6 – 5 = – 1
C31 = (– 1)3 + 1 12 – 10 = 2
C12 = (– 1)1 + 2 – 6 + 4 = 2
C22 = (– 1)2 + 1 – 4 – 5 = – 9
C32 = (– 1)3 + 1 – 8 – 15 = 23
C13 = (– 1)1 + 2 3 – 2 = 1
C23 = (– 1)2 + 1 2 + 3 = – 5
C33 = (– 1)3 + 1 4 + 9 = 13
adj A =
A – 1 =
A – 1 =
A – 1 =
Now the given equation can be written as:
A X B
Or, X = A – 1B
=
X =
Hence, x = 1,y = 2 and z = 3