2. Consider the following sets of vectors. Show that each set (i) contains the zero vector, (ii) is closed under addition and scalar multiplication. Then find a basis for each set and give the dimension. (a) W is the set of vectors of the form (-s, 2s, s). (b) W is the set of vectors of the form (2t - 2, 0, 1 - t). (c) H is the set of vectors of the form (2b, a, 3b) (d) H is the set of vectors of the form (-b + 2c, b, 4c)