polynomial-2

The constant polynomial whose coefficients are all equal to 0. The corresponding polynomial function is the constant function with value 0, also called the zero map. The zero polynomial is the additive identity of the additive group of polynomials.
The degree of the zero polynomial is undefined, but many authors conventionally set it equal to or . In Mathematica, Exponent[0, x] returns -Infinity.

Variable
A variable is a symbol on whose value a function, polynomial, etc., depends. For example, the variables in the function are and . A function having a single variable is said to be univariate, one having two variables is said to be bivariate, and one having two or more variables is said to be multivariate. In a polynomial, the variables correspond to the base symbols themselves stripped of coefficients and any powers or products.
The variables in a polynomial can be extracted using the Mathematica command Variables.
The field of all rational and irrational numbers is called the real numbers, or simply the "reals," and denoted . The set of real numbers is also called the continuum, denoted . The set of reals is called Reals in Mathematica, and a number can be tested to see if it is a member of the reals using the command Element[x, Reals], and expressions that are real numbers have the Head of Real.
The real numbers can be extended with the addition of the imaginary number i, equal to (-1)^1/2. Numbers of the form x+iy, where and are both real, are called complex numbers, which also form a field. Another extension which includes both the real numbers and the infinite ordinal numbers of Georg Cantor is the surreal numbers.