V1 = [4 1 3], v2 = [3 2 3], v3 = [7 1 2]
v1 = [0 1 4], v2 = [3 3 5]
(a) for what values of h is v3 in span {v1; v2}, and
(b) for what values of h is {v1; v2; v3}