Algebraic expression knowledge point (1) Algebraic expression, the first volume of junior one mathematics.
1 Algebraic expression: Algebraic expression is a general term for monomial and polynomial, and it is a part of rational formula. In rational expressions, there can be five operations: addition, subtraction, multiplication, division and multiplication, but in algebraic expressions, the divisor cannot contain letters.
2. Monomial: An algebraic expression composed of the product of numbers or letters is called a monomial, and a single number or letter is also called a monomial.
3. Polynomials: Algebraic expressions composed of several monomials are called polynomials.
4. Coefficient: The sum of the indices of all the letters in the monomial is called its number.
5. Times: The sum of the indexes of all variables in a single item is called the times of this single item.
6. Term: Each monomial that constitutes a polynomial is called a polynomial term.
7. Constant term: In polynomials, each term without letters is called a 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) Algebraic expression addition and subtraction: that is, addition and subtraction of monomials and polynomials can be accomplished by removing brackets and merging similar terms.
Algebraic expression addition and subtraction operation, if you encounter parentheses, first remove the parentheses, and then merge similar items.
1. Remove brackets: add and subtract several algebraic expressions. If there are brackets, remove them first, and then merge similar items.
If the factor outside the brackets is positive, the symbols in the original brackets are the same after the brackets are removed.
If the factor outside the bracket is negative, the sign in the original bracket is opposite after the bracket is removed.
2. Merge similar projects:
After merging similar items, the coefficients of the obtained items are the sum of the coefficients before merging, and the letter part remains unchanged.