let q be Real; :: thesis: ( q is Integer & q > 0 implies for r being Element of F_Complex st |.r.| = 1 & r <> [**1,0 **] holds
|.([**q,0 **] - r).| > q - 1 )
assume A1:
( q is Integer & q > 0 )
; :: thesis: for r being Element of F_Complex st |.r.| = 1 & r <> [**1,0 **] holds
|.([**q,0 **] - r).| > q - 1
let r be Element of F_Complex ; :: thesis: ( |.r.| = 1 & r <> [**1,0 **] implies |.([**q,0 **] - r).| > q - 1 )
assume that
A2:
|.r.| = 1
and
A3:
r <> [**1,0 **]
; :: thesis: |.([**q,0 **] - r).| > q - 1
set a = Re r;
set b = Im r;
A4:
((Re r) ^2 ) + ((Im r) ^2 ) = 1 ^2
by A2, COMPTRIG:7;
then
( Re r <> 1 & Re r <= 1 )
by A2, COMPLEX1:140;
then A6:
Re r < 1
by XXREAL_0:1;
A7:
( Re [**(q - (Re r)),(- (Im r))**] = q - (Re r) & Im [**(q - (Re r)),(- (Im r))**] = - (Im r) )
by COMPLEX1:28;
2 * q > (2 * q) * (Re r)
by A6, A1, XREAL_1:159;
then
- ((2 * q) * (Re r)) > - (2 * q)
by XREAL_1:26;
then
(- (2 * q)) + (q ^2 ) < (- ((2 * q) * (Re r))) + (q ^2 )
by XREAL_1:10;
then A8:
((q ^2 ) - ((2 * q) * (Re r))) + 1 > ((q ^2 ) - (2 * q)) + 1
by XREAL_1:10;
reconsider qc = [**q,0 **] as Element of F_Complex ;
A9:
|.(qc - r).| >= 0
by COMPLEX1:132;
|.(qc - r).| ^2 =
|.([**q,0 **] - [**(Re r),(Im r)**]).| ^2
by COMPLEX1:29
.=
|.[**(q - (Re r)),(0 - (Im r))**].| ^2
by POLYNOM5:6
.=
((q - (Re r)) ^2 ) + ((Im r) ^2 )
by A7, COMPTRIG:7
.=
((q ^2 ) - ((2 * q) * (Re r))) + 1
by A4
;
then
|.(qc - r).| ^2 > (q - 1) ^2
by A8;
hence
|.([**q,0 **] - r).| > q - 1
by A9, SQUARE_1:118; :: thesis: verum