let V be RealLinearSpace; for u, v being VECTOR of V st {u,v} is linearly-independent & u <> v holds
{u,(- v)} is linearly-independent
let u, v be VECTOR of V; ( {u,v} is linearly-independent & u <> v implies {u,(- v)} is linearly-independent )
A1:
- v = (- 1) * v
by RLVECT_1:16;
assume
( {u,v} is linearly-independent & u <> v )
; {u,(- v)} is linearly-independent
hence
{u,(- v)} is linearly-independent
by A1, Th19; verum