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


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