
theorem
  for a be Real holds frac (a*a) = frac ((2*a*frac a) - (frac a)*(frac a))
  proof
    let a be Real;
    frac (a*a) = frac ((a*frac a) + (a*frac a) - (frac a)*(frac a)) by FR1;
    hence thesis;
  end;
