What do the brackets [ and ] mean in this algebraic expression?

Question

I know that they are used when paranthesis are already being used (i.e. 9+[5(4-6)]22

But, I got a problem like this:

http://i36.tinypic.com/116thrs.jpg

There was no key for those sort of brackets, so I drew it.

Answer 1

Okay so you would add 3 and 0, 2 and 5, 4 and -3, and -1 and -4. all seperately. then put the sums in the same places the numbers were in the bracets and there you go.  I hope I explaned it well enough.

Answer 2

In this case, they indicate the numbers inside are a matrix.