1. Addition and subtraction of algebraic expressions

1, monomial: a formula that represents the product of numbers or letters, and a single number or letter is also called monomial;

2. Coefficient and frequency of single item: the numerical factor in single item is called the coefficient of single item;

The sum of all the letter indices in the monomial is called the number of times of the monomial;

3. Polynomial: The sum of several monomials is called polynomial;

4. Number and degree of polynomials: the number of monomials contained in a polynomial is the number of polynomial terms, and each monomial is called a polynomial term; In polynomials, the degree of the term with the highest degree is called the degree of polynomials;

5. Similar items: monomials with the same letters and the same letter index are similar items.

Second, the addition and subtraction of scores.

Although 1, general fraction and reduced fraction are all aimed at fractions, they are two opposite variants. Reduction is for one score, while general scores are for multiple scores; Simplification is to simplify fractions, and general fractions are to simplify fractions, thus unifying the denominator of each fraction.

2. Both general score and approximate score are deformed according to the basic properties of the score, and their similarity is to keep the value of the score unchanged.

3. The general denominator is written in the form of unexpanded continuous product, and the numerator multiplication is written in polynomial to prepare for further operation.

4. The basis of general score: the basic nature of score.

5. The key to general scores: determine the common denominator of several scores.

Usually, the product of the highest power of all factors of each denominator is taken as the common denominator, and such common denominator is called the simplest common denominator.

6. The total score of the analogy score is the total score of the score.

Turning several fractions with different denominators into fractions with the same denominator equal to the original fraction is called the general fraction of fractions.