Linear Algebra , algebra homework help

use the elementary row operation to reduce the following matrices.

No.1

3 -2 -1

2 -1 -1

4 3 -1

No.2

-2 -4 7

-3 -6 10

1 2 -3

No.3

-1 2 5 3 

1 0 -6 1

-1 2 2 -1

No.4

2 3 -2 1 3

1 2 -4 4 1 

2 3 0 0 2 

-1 2 2 3 6

thats for 1st

and also i have attached the 2nd one 

and i need explintion for each one.