The coefficient of the term becomes positive, and then according to the deformation about

Unequal inequality determines the location of the region (regulation:

The area indicated by the positive direction of the axis is above the straight line; On the contrary, there is a conclusion:

Positive coefficient:

Open;

Below. Example 3 Draw a set of inequalities.

The plane area represented by. Analysis: ① Inequality

The corresponding linear equation is

; inequality

The corresponding linear equation is

; Make a straight line in a plane rectangular coordinate system

and

(pictured).

② classify each inequality into inequality groups.

Positive term coefficient

or

(Move items). ③ About

Inequality of ()

) that is

(or

), the area above the straight line is the plane area represented by this inequality (Figure1); About; In all parts of; about

Inequality of ()

) that is

The area under the straight line is the plane area represented by this inequality (Figure 2).

④ The common * * * part is the plane area represented by the inequality group.

(2)

Normalization of term coefficient: same as (1), which does not mean that both sides are at the same time.

(or moving items) will be

The coefficient of the term becomes positive, and then according to the deformation about

Unequal inequality determines the regional status (regulation:

The area represented by the positive direction of the axis is the right side of the straight line; Contrary to the left) there is a conclusion:

Positive coefficient:

Right;

To the left Can be combined with example 3.

The term coefficient is normalized for easy understanding.