Mathematical mind map of the first volume of the seventh grade: mathematical mind map of the algebraic expression of the first volume of the seventh grade: intersection line and parallel line: mathematical mind map of the first volume of the seventh grade: mathematical mind map of the first volume of the seventh grade triangle: the relationship between variables: mathematical knowledge points of the algebraic expression of the first volume of the seventh grade (1) algebraic expression
1. Algebraic expression: monomials and polynomials are collectively called algebraic expressions.
2. Monomial: The formula consisting of the product of numbers and letters is called monomial. A single number or letter is also a monomial.
3. Coefficient: In a single item, the numerical factor is called the coefficient of this single item.
4. Times: The sum of the indices of all the letters in the monomial is called the times of this monomial.
5. Polynomial: The sum of several monomials is called polynomial.
6. Term: Each monomial that constitutes a polynomial is called a polynomial term.
7. Constant term: the term without letters is called constant term.
8. Degree of Polynomial: In a polynomial, the degree of the term with the highest degree is called the degree of this polynomial.
9. Similar terms: In polynomials, terms with the same letters and the same index of the same letters are called similar terms.
10. Merging similar items: Merging similar items in polynomials into one item is called merging similar items.
(2) Addition and subtraction of algebraic expressions
When adding and subtracting algebraic expressions, if you encounter parentheses, remove them first, and then merge similar items.
1. bracket removal: Generally speaking, several algebraic expressions are added and subtracted. If there are brackets, remove them first, and then merge similar items.
If the factor outside the brackets is positive, the symbols of the items in the original brackets are the same as the original symbols after the brackets are removed. If the factor outside the brackets is negative, the symbols of the items in the original brackets are opposite to those after the brackets are removed.
2. Merging similar items: Merging similar items in polynomials into one item is called merging similar items.