reserve x,a,b,c for Real,
  n for Nat,
  Z for open Subset of REAL,
  f, f1,f2 for PartFunc of REAL,REAL;

theorem Th3:
  (1/x) #Z n = 1/(x #Z n)
proof
  (1/x) #Z n = (1/x) |^ n by PREPOWER:36
    .=1/x |^ n by PREPOWER:7;
  hence thesis by PREPOWER:36;
end;
