let X, Y be RealNormSpace; for f, h being Point of
for a being Real holds
( h = a * f iff for x being VECTOR of holds h . x = a * (f . x) )
let f, h be Point of ; for a being Real holds
( h = a * f iff for x being VECTOR of holds h . x = a * (f . x) )
let a be Real; ( h = a * f iff for x being VECTOR of holds h . x = a * (f . x) )
reconsider f1 = f as VECTOR of ;
reconsider h1 = h as VECTOR of ;
( h = a * f iff h1 = a * f1 )
;
hence
( h = a * f iff for x being VECTOR of holds h . x = a * (f . x) )
by Th30; verum