Linear Algebra cheat sheet 1 Vector spaces In the following k = Q,R or C. Definition. A k-vector space is an abelian group V together with a map k 1V ! V, (l,v) 7!lv, satisfying 1. l(v 1 +v2) = lv 1 +lv2, 2. (l 1 +l2)v = l 1v +l2v, 3. (lm)v = l(mv), 4.1 v = v, for all l,m,l 1,l2 2k and all v,v 1,v2 2V. A subgroup U V is a linear subspace if lu ...