2f x +f 1-x x, f x-1 x2 f x, f x x 2 - x -1, f x 2f x-1 +1, f x 2f x/2 +x, f x f x-1 +2f x-2, f' x 2f x, f x+ 2 2f x, f x+1 2f x, f x x 1/2, f x x 3-x 2f' 1, f x x2-2x-1, f x 2/x, f x x2-1, f x 2 x-1/2 x+1
2f x f 1-x x2. There are any references about 2f x f 1-x x2 in here. you can look below.