Inverse of coefficient matrix question!?

Question

how do i solve the following system of equations using the inverse of the coefficient matrix? 

2x+4y+6z=4
-x-4y-3z=8 
y-z =-4

Answer 1

Step 1:

The system of equations are

Write the equations into matrix form , where is coefficient matrix,

is variable matrix and is constant matrix.

Definition of inverse matrix :

If is an then , where .

Let , then .

, then has an inverse.

Step 2:

Cofactor of is

Cofactor of

.

.

Step 3:

Find .

Solution :

The inverse of the is