Let
α1=(1,1,−2,1),α2=(3,0,4,−1),α3=(−1,2,5,2).
Let
α=(4,−5,9,−7),β=(3,1,−4,4),γ=(−1,1,0,1).
(a) Which of the vectors α,β,γ are in the subspace of R4 spanned by the αi?
(b) Which of the vectors α,β,γ are in the subspace of C4 spanned by the αi?
(c) Does this suggest a theorem?