
theorem Th7:
  for n being Nat holds 2 * (2 - (3 / (n + 1))) < 4
proof
  let n be Nat;
  assume 2 * (2 - (3 / (n + 1))) >= 4;
  then 2 * (2 - (3 / (n + 1))) / 2 >= 4 / 2 by XREAL_1:72;
  then 2 - (3 / (n + 1)) - 2 >= 2 - 2 by XREAL_1:9;
  then --- (3 / (n + 1)) >= 0;
  hence thesis by XREAL_1:139;
end;
