x? +1 is a quadratic polynomial, so its molecular polynomial is a linear polynomial CX+D.
The principle is polynomial division, and the division principle is the sum of true fractions (the definition of true fractions is similar to that of true fractions). Then the numerator must be the remainder of the denominator divided by a polynomial, and the highest degree that the numerator can reach will be less than the denominator 1, so if the denominator is a polynomial of degree n, then the numerator must be a polynomial of degree N- 1.