Linear algebra, please help

Is there a spanning set for the following. Are they subspaces? Why?

{ [ a] [b] ................}
{ [-b] [c] | a + c = 0 }

The periods are just for formating

i will assume that this is a matrix.....spanning set is matrix with 1st row = [ 1..0] and 2nd is [ 0 .. -1] combined with the matrix whose 1st row = [ 0 ..1 ] and 2nd [ -1 ...0 ]


closed under addition and scalar multiplication