let K be non empty doubleLoopStr ; :: thesis: for V, W being non empty VectSpStr of K
for f being Form of V,W
for a being Element of K
for v being Vector of V holds FunctionalFAF ((a * f),v) = a * (FunctionalFAF (f,v))
let V, W be non empty VectSpStr of K; :: thesis: for f being Form of V,W
for a being Element of K
for v being Vector of V holds FunctionalFAF ((a * f),v) = a * (FunctionalFAF (f,v))
let f be Form of V,W; :: thesis: for a being Element of K
for v being Vector of V holds FunctionalFAF ((a * f),v) = a * (FunctionalFAF (f,v))
let a be Element of K; :: thesis: for v being Vector of V holds FunctionalFAF ((a * f),v) = a * (FunctionalFAF (f,v))
let w be Vector of V; :: thesis: FunctionalFAF ((a * f),w) = a * (FunctionalFAF (f,w))

now

let v be Vector of W; :: thesis: (FunctionalFAF ((a * f),w)) . v = (a * (FunctionalFAF (f,w))) . v
thus (FunctionalFAF ((a * f),w)) . v = (a * f) . (w,v) by Th9
.= a * (f . (w,v)) by Def4
.= a * ((FunctionalFAF (f,w)) . v) by Th9
.= (a * (FunctionalFAF (f,w))) . v by HAHNBAN1:def 9 ; :: thesis: verum

end;

hence FunctionalFAF ((a * f),w) = a * (FunctionalFAF (f,w)) by FUNCT_2:113; :: thesis: verum