Rational numbers 1, numbers like 5, 1, 2 … are called positive numbers, all of which are greater than 0. In order to highlight the symbols of numbers, you can add a "+"sign before positive numbers, such as +5,+1.2.
2. Numbers with "-"in front of positive numbers are called negative numbers, such as-10, -3, ….
3,0 is neither positive nor negative.
4. Integers and fractions are collectively called rational numbers.
Number axis 1, number axis: a straight line that defines the origin, positive direction and unit length.
2. Three elements of the number axis: origin, positive direction and unit length.
3. All rational numbers can be represented by points on the number axis.
4. Inverse number: If two numbers differ only in sign, then we call one of them the inverse number of the other number, which also means that these two numbers are inverse numbers.
Addition and subtraction of algebraic expressions 1, monomial: in algebraic expressions, if only multiplication (including power) operations are involved. Or algebraic expressions that contain division but do not contain letters in division are called monomials.
2. The coefficient and times of single item: the non-zero numerical factor in single item is called the numerical coefficient of single item, which is simply referred to as the coefficient of single item; When the coefficient is not zero, the sum of all the letter indexes in the single item is called the number of times of the single item.
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. Algebraic expression: Any algebraic expression that does not contain division operation or contains division operation but does not contain letters in the division formula is called algebraic expression.
Four. Algebraic expressions are classified as?
6. Similar items: monomials with the same letters and the same letter index are similar items.
7. Rules for merging similar items: When the coefficients are added, the letters and the indexes of letters remain unchanged.
8. Rules for deleting (adding) brackets: When deleting (adding) brackets, if there is a "+"sign before the brackets, all items in the brackets remain unchanged; If there is a "-"before the brackets, all items in the brackets should be changed.
9. Algebraic addition and subtraction: Algebraic addition and subtraction is actually to combine similar terms of polynomials on the basis of removing brackets.
10, ascending and descending order of polynomials: arranging the terms of a polynomial according to the exponent of a letter from small to large (or from large to small) is called ascending order (or descending order) of this letter. Note: The final result of polynomial calculation should generally be ascending power (or descending power arrangement).
One-dimensional linear equation 1, equation and equivalence: the equation connected by "=" is called equation. Note: "Equivalent value can be substituted"!
2, the nature of the equation:
Properties of equation 1: Add (or subtract) the same number or the same algebraic expression on both sides of the equation, and the result is still an equation;
Property 2 of the equation: both sides of the equation are multiplied (or divided) by the same non-zero number, and the result is still an equation.
3. Equation: An equation with an unknown number is called an equation.
4. Solution of the equation: the value of the unknown quantity that makes the left and right sides of the equation equal is called the solution of the equation; Note: "The solution of the equation can be substituted"!
5. Moving term: after changing the sign, moving the term of the equation from one side to the other is called moving term. The shift term is based on the equality attribute 1.
6. One-dimensional linear equation: An integral equation with only one unknown number, degree 1 and non-zero coefficient is a one-dimensional linear equation.
7. The standard form of one-dimensional linear equation: ax+b=0(x is unknown, a and b are known numbers, a≠0).
The above is the content of the first volume of Grade One, I hope I can help you.