Determine whether the set S spans R2. If the set does not span give a geometric description of the subspace that it does span.
1. S = { (2, 1), (-1, 2) }
2. S = { (1, 3), (-2, -6), (4, 12)}
3. S = { (-3, 5) }
4. S = { (5, 0), (5, -4) }
5. S = { (-1, 2), (2, -4) }