let a, b be Real; sqr <*a,b*> = <*(a ^2),(b ^2)*>
dom sqrreal = REAL
by FUNCT_2:def 1;
then A1:
rng <*a,b*> c= dom sqrreal
;
A2:
dom <*(a ^2),(b ^2)*> = {1,2}
by FINSEQ_1:2, FINSEQ_1:89;
A3:
for i being object st i in dom <*(a ^2),(b ^2)*> holds
(sqr <*a,b*>) . i = <*(a ^2),(b ^2)*> . i
dom (sqr <*a,b*>) =
dom (sqrreal * <*a,b*>)
by RVSUM_1:def 8
.=
dom <*a,b*>
by A1, RELAT_1:27
.=
{1,2}
by FINSEQ_1:2, FINSEQ_1:89
;
hence
sqr <*a,b*> = <*(a ^2),(b ^2)*>
by A3, FINSEQ_1:2, FINSEQ_1:89, FUNCT_1:2; verum