The concepts and properties of 1, square root and arithmetic square root;

⑴ Concept: If x2 = a, then x is the square root of a, which is called the arithmetic square root of a..

⑵ Properties: ① When a≥0, ≥ 0; When a < 0, it is meaningless; ②()2 = a； ③ =|a| .

2, the concept of cube root and its properties:

⑴ Concept: If x3 = A, then X is the cube root of a, which is recorded as:

(2) Properties: ① = a; ②()3 = a； ③ =-

3. The concept and classification of real numbers:

⑴ Concept: Real number is a general term for rational number and irrational number;

(2) Classification:

4. Concepts related to real numbers:

In the real number range, the meanings of reciprocal, reciprocal and absolute value are exactly the same as those in the rational number range; In the range of real numbers, the algorithm of rational numbers is as effective as the algorithm law.

5, arithmetic square root algorithm:

Second, simple translation and rotation.

Three, quadrilateral:

1, classification of polygons

2. Important knowledge points in this chapter:

Fourth, the determination of the position:

Five, a function:

Six, binary linear equations:

1, the basic idea of solving the equation is elimination, and the basic methods of elimination are: ① substitution elimination method; ② addition, subtraction and elimination method, in addition to mirror image method;

2. The key to solving application problems with equations is to find the equation relationship;

3. When solving application problems, it is divided into four steps: setting, arranging, solving and answering;

4. Every binary linear equation can be regarded as a linear function. Finding the solution of binary linear equations can be regarded as finding the intersection of two linear function images.

VII. Representative data:

1, definition and calculation method of average value:

(1) Generally speaking, for n numbers x 1, x2, …, xn, we call it the arithmetic average of these n data, and write it as.

(2) If x 1 appears f 1 time, x2 appears f2 times, …, xk appears fk times, it is called the weighted average of x 1, x2, …, xk;

2. The difference and connection between arithmetic average and weighted average: arithmetic average is a special case of weighted average (its special feature is that the weights of each item are equal). In practical problems, when the weights of each item are not equal, the weighted average should be used when calculating the average, and when the weights of each item are equal, the arithmetic average should be used when calculating the average.

3. Median and mode

(1) Median refers to one data (or the average of the two middle data), and n data are arranged in order of size.

(2) Mode refers to the data with the highest frequency in a group of data.