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

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


Co-factors of the elements of first row of | A | are
       
i.e.     1, 5, 4 respectively.
Co-factors of the elements of second row of  are 
 
i.e. 1. – 1, 1 respectively.
Co-factors of the elements of third row of | A | are

i.e. 0, – 3, – 3 respectively.