let x be Real; ( x > 0 implies exp_R . x > x + 1 )
assume AA:
x > 0
; exp_R . x > x + 1
set r = 1;
set f = Maclaurin (exp_R,].(- 1),1.[,x);
A4:
exp_R . x = Sum (Maclaurin (exp_R,].(- 1),1.[,x))
by TAYLOR_2:16;
A2: (Maclaurin (exp_R,].(- 1),1.[,x)) . 0 =
(x |^ 0) / (0 !)
by TAYLOR_2:8
.=
1
by NEWTON:4, NEWTON:12
;
A3: (Maclaurin (exp_R,].(- 1),1.[,x)) . 1 =
(x |^ 1) / (1 !)
by TAYLOR_2:8
.=
x
by NEWTON:13
;
SS:
Maclaurin (exp_R,].(- 1),1.[,x) is absolutely_summable
by TAYLOR_2:16;
then A6: Sum (Maclaurin (exp_R,].(- 1),1.[,x)) =
((Partial_Sums (Maclaurin (exp_R,].(- 1),1.[,x))) . 1) + (Sum ((Maclaurin (exp_R,].(- 1),1.[,x)) ^\ (1 + 1)))
by SERIES_1:15
.=
(((Partial_Sums (Maclaurin (exp_R,].(- 1),1.[,x))) . 0) + ((Maclaurin (exp_R,].(- 1),1.[,x)) . (0 + 1))) + (Sum ((Maclaurin (exp_R,].(- 1),1.[,x)) ^\ (1 + 1)))
by SERIES_1:def 1
.=
(1 + x) + (Sum ((Maclaurin (exp_R,].(- 1),1.[,x)) ^\ (1 + 1)))
by A2, A3, SERIES_1:def 1
;
( Maclaurin (exp_R,].(- 1),1.[,x) is positive-yielding & Maclaurin (exp_R,].(- 1),1.[,x) is summable )
by MacPositive, AA, SS;
hence
exp_R . x > x + 1
by A4, A6, XREAL_1:29, Th36; verum