( 5/9 + 55/99 + 555/999 )² : 5/9 - 111/500 : ( 1/5 + 1/50 + 1/500 ) ^n = 4
(5/3)² * 9/5 - 111/500 : (111/500 )^n = 4
25/9 * 9/5 - (111/500) ^ -n+1 = 4
5 - ( 111/500)^ -n+1 = 4
-(111/500)^-n+1 = 4-5
-(111/500)^-n+1 = 1
(111/500)^-n+1 = (111/500)^0
-n+1=0
-n=-1
n=1
Verf:
( 5/9 + 55/99 + 555/999 )² : 5/9 - 111/500 : ( 1/5 + 1/50 + 1/500 )^1 =
= (5/3)² * 9/5 - 111/500 : (111/500) ^1 =
= 25/9 * 9/5 - 1 =
= 5-1 = 4