reserve x for set;
reserve a,b,c,d,e,r1,r2,r3,r4,r5,r6 for Real;
reserve V for RealLinearSpace;
reserve u,v,v1,v2,v3,w,w1,w2,w3 for VECTOR of V;
reserve W,W1,W2 for Subspace of V;

theorem
  {u,w,v} is linearly-independent & u <> v & u <> w & v <> w implies {u,
  w,- v} is linearly-independent
proof
  - v = (- 1) * v by RLVECT_1:16;
  hence thesis by Th27;
end;
