( x^4 - 4 x³ + 2 x² - 4 x + 1 ) : ( x² + 1 ) = x² - 4 x + 1
- x^4 - x²
------------------------
- 4 x³ + x² - 4 x
4 x³ + 4 x
-----------------------
x² + 1
- x² - 1
----------------
R ( x ) = 0
( x^4 - 4 x³ + 2 x² - 4 x + 1) = ( x² + 1 ) ( x² - 4 x + 1 )