292. Use matrix method to solve the following system of equations:
x + y – z = 1
3 x + y – 2z = 3
x – y – z = – 1

The given equations are
x + y – z = 1
3x + y – 2z = 3
x – y – z = – 1
These equations can be written as
             

or         



Co-factors of the elements of first row of | A | are

   i.e.,  – 3  1, – 4 respectively
Co-factors of the elements of second row of | A | are

i.e. 2,  0, 2 respectively
Co-factors of the elements of third row of | A | are

i.e. – 1, – 1, – 2 respectively