Bases for Subspaces of Rn in problems 1-3, find a basis and the dimension of the given subspaces of Rn?
1. {[a, 0, b, a - b + c] | a, b, c ( R} as a subspace of R4
2. {[a, a - b, 2a + 3b] | a, b, ( R} as a subspace of R3
3. {[x + y + z, x + y, 4z, 0] | x, y, z ( R} as a subspace of R4