Show that if S1 (S subscript 1) and S2 are subsets of a vector space V such that S1 ⊆ S2, then span (S1) ⊆ span (S2). In particular, if S1 ⊆ S2 and span (S1) = V, deduce that span (S2) = V.
Show that if S1 (S subscript 1) and S2 are subsets of a vector space V such that S1 ⊆ S2, then span (S1) ⊆ span (S2). In particular, if S1 ⊆ S2 and span (S1) = V, deduce that span (S2) = V.