[(4X^(N+1)-1/2Y)^2+4Y(X^N-Y/16)]÷(4X^2)
=[16X^(2N+2)-4X^(N+1)Y+Y^2/4+4X^NY-Y^2/4]÷(4X^2)
=[16X^(2N+2)-4X^(N+1)Y+4X^NY]÷(4X^2)
=4X^(2N)-Y*X^(N-1)+Y*X^(N-2)