let A be closed-interval Subset of REAL ; integral (exp_R (#) exp_R ),A = (1 / 2) * (((exp_R . (upper_bound A)) ^2 ) - ((exp_R . (lower_bound A)) ^2 ))
exp_R | A is continuous
;
then A1:
exp_R `| REAL is_integrable_on A
by Lm8, Th32, INTEGRA5:11;
( (exp_R `| REAL ) | A is bounded & [#] REAL is open Subset of REAL )
by Lm8, Th32, INTEGRA5:10;
then integral (exp_R (#) exp_R ),A =
(((exp_R . (upper_bound A)) * (exp_R . (upper_bound A))) - ((exp_R . (lower_bound A)) * (exp_R . (lower_bound A)))) - (integral (exp_R (#) exp_R ),A)
by A1, Th32, INTEGRA5:21, SIN_COS:71
.=
(((exp_R . (upper_bound A)) ^2 ) - ((exp_R . (lower_bound A)) * (exp_R . (lower_bound A)))) - (integral (exp_R (#) exp_R ),A)
.=
(((exp_R . (upper_bound A)) ^2 ) - ((exp_R . (lower_bound A)) ^2 )) - (integral (exp_R (#) exp_R ),A)
;
hence
integral (exp_R (#) exp_R ),A = (1 / 2) * (((exp_R . (upper_bound A)) ^2 ) - ((exp_R . (lower_bound A)) ^2 ))
; verum