Let W be the set of all 2x2 matrices of the form [a -b]. Then under the usual matrix operations W is
1. Not a vector space
2. a vector space of dimension 1.
3. a vector space of dimension 2.
4. a vector space of dimension 3.
5. a vector space of dimension 4.
The solution gives detailed steps on showing the given matrix is a vector space and then finding its dimension.