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【 eighth grade mathematics knowledge points 20 18 】 summary of eighth grade history knowledge points 20 18
The authority of Grade Two released the knowledge points of Grade Eight Mathematics Book 20 18. For more information about the knowledge points of the eighth grade math book 20 18, please visit the second grade junior high school network. Introduction: This article about the knowledge points of the eighth grade mathematics volume 2 (20 18) was compiled by Da Fan. I hope I can help you!

Chapter 1 One-dimensional linear inequalities and one-dimensional linear inequalities.

1. Generally speaking, formulas connected by the symbol ""(or "≥") are called inequalities.

The value of the unknown quantity that can make the inequality hold is called the solution of the inequality. The solution of inequality is not unique. All that satisfy the inequality are liberated together to form the solution set of the inequality. The process of finding the solution set of inequality is called solving inequality.

An inequality group consisting of several linear inequality groups is called a linear inequality group.

Solution set of inequality group: the common part of each inequality solution set in linear inequality group.

The basic property of equation 1: Add (or subtract) the same number or algebraic expression on both sides of the equation, and the result is still an equation. Basic property 2: the result of multiplying or dividing the same number on both sides of an equation (the divisor is not 0) is still an equation.

Second, basic inequality.

Property 1. Add (or subtract) the same algebraic expression on both sides of the inequality, and the direction of the inequality is unchanged. (Note: Transposition requires sign change, but the equal sign remains the same. )

Property 2: Both sides of the inequality are multiplied by (or divided by) the same positive number, and the direction of the inequality remains unchanged.

Property 3: When both sides of the inequality are multiplied by (or divided by) the same negative number, the direction of the inequality changes. Basic properties of inequality, if a >;; B, then a+c > b+ c; If a>b and c>0 are AC & GTBC IF C.

Other properties of inequality: reflectivity: if a >;; B, then B transitivity: If a>b and b>c, then a>c

Third, steps to solve inequality:

1, denominator; 2. Remove the brackets; 3. Transfer projects and merge similar projects; 4. The coefficient is 1. Fourth, the steps to solve the inequality group: 1, the solution set of inequality 2, indicating the solution set of inequality on the same axis. 5. Enumerate the general steps of solving practical problems with linear inequality of one variable: (1) examining questions; (2) Set an unknown number and find an (unequal) relationship; (3) setting independent variables, setting inequalities (groups) (according to inequalities) (4) solving inequality groups; Test and answer.

VI. Frequently Asked Questions:

1, find the nonnegative solution of 4x-67x- 12. 2. It is known that the solution of 3(x-a)=x-a+ 1r is suitable for 2(x-5)8a, and the range of a is found.

The solution of 3.3x+m-2(m+2)=3m+x is between -5 and 5.

Chapter II Factorization

1. formula: 1, ma+mb+mc=m(a+b+c)2, A2-B2 = (a+b) (a-b) 3, A2+2ab+B2 = (a+b) 2. Convert a polynomial into the product of several algebraic expressions. 1. Turning the product of several algebraic expressions into a polynomial is a multiplication operation. 2. Turning a polynomial into the product of several algebraic expressions is factorization. 3.ma+mb+mcm(a+b+c)4。 Factorization and algebraic expression multiplication are deformations in opposite directions.

3. Let all terms of a polynomial contain the same factor, which is called the common factor of each term of this polynomial. To decompose a factor by the common factor method is to convert a polynomial into a monomial and then multiply it with this polynomial. The general steps to find the common factor are: (1) If each coefficient is an integer coefficient, take the greatest common factor of the coefficient; (2) Taking the same letter, the index of the letter is lower; (3) Take the same polynomial with lower exponent. (4) The product of all these factors is the common factor.

4. The general steps of factorization are as follows: (1) If there is a "-",first extract the "-",if the polynomial has a common factor, then extract the common factor. (2) If the polynomial has no common factor, choose the square difference formula or the complete square formula according to the characteristics of the polynomial. (3) Every polynomial must be decomposed until it can no longer be decomposed.

5. A formula in the form of A2+2ab+b2 or A2-2AB+B2 is called a completely flat mode. Method of factorization: 1, method of extracting common factor. 2. Use the formula method.