Solve the following system of equations by matrix method:

3x + y = 7


5x + 3y = 12

The above system of equations can be written as


or AX = B


Where A = B = and X =


|A| = 9 – 5 = 4


So, the above system has a unique solution, given by


X = A – 1B


Let Cij be the cofactor of aijin A, then


C11 = (– 1)1 + 1 3 = 3


C12 = (– 1)1 + 2 5 = – 5


C21 = (– 1)2 + 1 1 = – 1


C22 = (– 1)2 + 2 3 = 3


Also, adj A =


=


A – 1 =


A – 1 =


Now, X = A – 1B






Hence, X = Y =


1