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.
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