Question

2 1 -1 8
1 -1 1 -2
1 1 2 0. Find x,y,z by using matrices.
This is the augmented form

Answer 1

Use row operations to reduce the 3 columns on the left to the identity matrix. Do you know how to do that?

Answer 2

Somewhat. I just don't know which columns to combine or reduce with

Answer 3

make Row1 become Row1-Row3

Answer 4

2 1 -1 8
1 -1 1 -2
1 1 2 0

If you subtract row 3 from row 1 you get

1 0 -3 8
1 -1 1 -2
1 1 2 0

Continue doing row operations until you end up with

1 0 0 a
0 1 0 b
0 0 1 c

In most cases you will be adding multiples of one row to another or multiplying a row by a number.