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


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