Can anyone help me with this problem? I've spent over an hour and got stuck (or screwed up). Thanks.

Please show the steps...


[1 2 -1 4 6 -2]
[-2 1 4 -2 9 10]
[3 4 -5 8 12 -12]
[1 -3 1 8 9 17]
[5 2 3 -6 -9 4]