Solve the following system of equations by matrix method:
2x + 6y = 2
3x – z = – 8
2x – y + z = – 3
The given system can be written in matrix form as:
or A X = B
A = , X =
and B =
Now, |A| = 2
= 2(0 – 1) – 6(3 + 2)
= – 2 – 30
= – 32
So, the above system has a unique solution, given by
X = A – 1B
Cofactors of A are:
C11 = (– 1)1 + 1 0 – 1 = – 1
C21 = (– 1)2 + 16 + 0 = – 6
C31 = (– 1)3 + 1 – 6 = – 6
C12 = (– 1)1 + 2 3 + 2 = 5
C22 = (– 1)2 + 1 2 – 0 = 2
C32 = (– 1)3 + 1 – 2 – 0 = 2
C13 = (– 1)1 + 2 – 3 – 0 = – 3
C23 = (– 1)2 + 1 – 2 – 12 = 14
C33 = (– 1)3 + 1 0 – 18 = – 18
adj A =
=
A – 1 =
Now, X = A – 1B =
X =
X =
X =
Hence, X = – 2,Y = 1 and Z = 2