y 2 ( x ) = 0 , y 1 ( x ) = 1 ,

q ( x ) = x 2 + 1 , r ( x ) = x 2 ,

y ( x ) = x 2 + 1 , y 2 ( x ) = 1 , y 1 ( x ) = x 2 + 1 ,

P ( x ) = x 6 + x 4 + x + 1 , A ( x ) = x 2 .