let x, y, a be Real; for vx being Element of REAL 2 st vx = <*x,y*> holds
a * vx = <*(a * x),(a * y)*>
let vx be Element of REAL 2; ( vx = <*x,y*> implies a * vx = <*(a * x),(a * y)*> )
reconsider x1 = x, y1 = y as Element of REAL ;
assume
vx = <*x,y*>
; a * vx = <*(a * x),(a * y)*>
hence a * vx =
<*((a multreal) . x1),((a multreal) . y1)*>
by FINSEQ_2:40
.=
<*(a * x1),((a multreal) . y1)*>
by RVSUM_1:19
.=
<*(a * x),(a * y)*>
by RVSUM_1:19
;
verum