let f be PartFunc of REAL ,REAL ; for r being Real st f is convergent_in+infty holds
( r (#) f is convergent_in+infty & lim_in+infty (r (#) f) = r * (lim_in+infty f) )
let r be Real; ( f is convergent_in+infty implies ( r (#) f is convergent_in+infty & lim_in+infty (r (#) f) = r * (lim_in+infty f) ) )
assume A1:
f is convergent_in+infty
; ( r (#) f is convergent_in+infty & lim_in+infty (r (#) f) = r * (lim_in+infty f) )
A2:
now let seq be
Real_Sequence;
( seq is divergent_to+infty & rng seq c= dom (r (#) f) implies ( (r (#) f) /* seq is convergent & lim ((r (#) f) /* seq) = r * (lim_in+infty f) ) )assume that A3:
seq is
divergent_to+infty
and A4:
rng seq c= dom (r (#) f)
;
( (r (#) f) /* seq is convergent & lim ((r (#) f) /* seq) = r * (lim_in+infty f) )A5:
rng seq c= dom f
by A4, VALUED_1:def 5;
then A6:
lim (f /* seq) = lim_in+infty f
by A1, A3, Def12;
lim_in+infty f = lim_in+infty f
;
then A7:
f /* seq is
convergent
by A1, A3, A5, Def12;
then
r (#) (f /* seq) is
convergent
by SEQ_2:21;
hence
(r (#) f) /* seq is
convergent
by A5, RFUNCT_2:24;
lim ((r (#) f) /* seq) = r * (lim_in+infty f)thus lim ((r (#) f) /* seq) =
lim (r (#) (f /* seq))
by A5, RFUNCT_2:24
.=
r * (lim_in+infty f)
by A7, A6, SEQ_2:22
;
verum end;
for r1 being Real ex g being Real st
( r1 < g & g in dom (r (#) f) )
hence
r (#) f is convergent_in+infty
by A2, Def6; lim_in+infty (r (#) f) = r * (lim_in+infty f)
hence
lim_in+infty (r (#) f) = r * (lim_in+infty f)
by A2, Def12; verum