4 0 - 1 4

- 1 2 1 0

-4 2 - 1 4

In line 2, line 3 and line 4, add lines 1 ×-2, 1/2, 2.

2 - 1 1 -2

0 2 -3 8

0 32 32 - 1

0 0 1 0

In line 3, add line 2 ×-3/4.

2 - 1 1 -2

0 2 -3 8

0 0 154 -7

0 0 1 0

Line 3 Exchange Line 4-

2 - 1 1 -2

0 2 -3 8

0 0 1 0

0 0 154 -7

In the fourth line, add the third line ×- 15/4-

2 - 1 1 -2

0 2 -3 8

0 0 1 0

0 0 0 -7

Multiply the main diagonal by 28.