Polynomial

A polynomial over a commutative ring $A$ is a formal expression
$$P=\sum_{i=0}^n a_i X^i=a_0+a_1 X+a_2 X^2+\cdots+a_n X^n$$where the $a_{i}$ belong to $A$ and $a_{n}\neq 0$. $n$ is called the degree of $P$.

Remarks

• The set of all polynomials in $X$ with coefficients in $A$ is denoted $A[X]$.