One. Monomial: The product of numbers or letters is called a monomial (a single number or letter is also a monomial). The numerical factor in a single item is called the coefficient of the item. The sum of the exponents of all letters is called the degree of this monomial. The zeroth power of any nonzero number is equal to 1.

Note: 1, the formula with unknown denominator is not a monomial. Because the monomial is an algebraic expression, and the formula with unknown denominator is a fraction. For example, 1/x is not a monomial.

2. A single number or letter is also a monomial. For example, 1 and x^2y are also monomials.

Two. Algebraic expression: Algebraic expression is a part of rational expression, which can contain four operations: addition, subtraction, multiplication and division, but in algebraic expression, divisor cannot contain letters. Monomial and polynomial are collectively called algebraic expressions.

Three. Polynomial: A formula consisting of the sum of several monomials is called a polynomial (in subtraction, subtracting a number equals adding its reciprocal). Each monomial in a polynomial is called a polynomial term, and the highest degree of these monomials is the degree of this polynomial.

Four. Monomial and polynomial are collectively called algebraic expressions.

Hope to adopt