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 =