Use Theorem 5.2.4 to show that v1 = (1, 6, 4), v2 = (2, 4, -1), v3 = (-1, 2, 5), and w1 = (1, -2, -5), w2 = (0, 8, 9) span the same sub space of R3.
Theorem 5.2.4
If S = {v1, v2,..., vr} and S' = {w1, w2,..., wk} are two sets of vectors in a vector space V, then
span {v1, v2,..., vk} = span{w1, w2,..., wk}
if and only if each vector in S is a linear combination of those in S′ and each vector in S′ is a linear combination of those in S.