1. Variables and functions

2.

3. Look at equations (groups) and inequalities from the functional point of view.

We call the amount of numerical change a variable.

Some values are always the same, which we call.

Generally speaking, in a change process, if there are two variables X and Y, and each value Y of X has a unique and definite value, we say that X is.

Y is a function of x, if y=b when x=a, then when.

When the function value is.

Generally speaking, a function in the form of y = kx (where k is a constant and k is not equal to 0) is called a linear function.

When k>0, the straight line y=kx passes through the third,

, rising from left to right, that is, y increases with the increase of x; When k < 0, the straight line y=kx passes through the second and the first.

From left to right, remember that y decreases as x increases.

data description

1. Several common

2. Describe the data with charts.

3. Project learning

Generally speaking, we call the number of data falling in different groups the number of the groups.

The ratio to the total data is frequency.

We call the number of divided groups the number of groups, and the difference between the two endpoints of each group is the group distance.

some

Characteristics of:

1. Bar chart features: you can display the specific data of each group.

2.

Features: It can display the percentage of parts in the total.

3.

Features: It can display the changing trend of data.

4.

Features: It can display the distribution of data.

1.

2.

Conditions of

3.

Nature of

A triangle that can completely coincide is called congruent triangles.

The essence of congruent triangles;

The corresponding edges of 1. congruent triangles are equal.

2. congruent triangles's

(to) equal to ...

Congruent triangles's judgment theorem;

1. There are three equilateral triangular congruences (SSS).

2. Two sides and their included angles correspond to the congruence (SAS) of two triangles.

3. The congruence (ASA) corresponding to two corners and two sides of two triangles.

4. congruence of two triangles, in which two angles and the corresponding sides of one angle are equal.

5. The hypotenuse and the right-angled side correspond to the congruence (HL) of two right-angled triangles.

Nature:

The distance from the point on the plane to both sides of the corner is equal.

1.

2.

change

3. isosceles triangle

The parts on both sides of a straight line can overlap with each other. This figure is called

This straight line is its axis of symmetry.

A straight line passing through the midpoint of a line segment and perpendicular to the line segment is called this line segment.

1.

Addition and subtraction of

2.

multiply operation

3.

4.

5.