Teaching objectives

1, master the solution of linear inequality group, and use linear inequality group to solve related practical problems;

2. Understand the general problem-solving steps of the application problems of the linear inequality group of one variable, and gradually form the ability to analyze and solve problems;

3. Experience the fun of mathematics learning and the value of a set of linear inequalities in solving practical problems.

Teaching difficulties

Correctly analyze the inequality relations in practical problems and list the inequality groups.

Knowledge focus

Establish a mathematical model of inequality group to solve practical problems.

Explore practical problems

Show example 2 on page 145 of the textbook (omitted)

Q: (1) How to understand the quantitative meaning of "unable to complete the task"?

(2) How to understand the quantitative significance of "completing the task ahead of schedule"?

(3) How are you going to solve this problem? What inequalities are listed?

Teachers and students discuss solution 2 together.

Inductive summary

1, textbook 146, Induction (omitted).

2. Do you think that enumerating one-dimensional linear inequalities is the same as enumerating two-dimensional linear equations to solve application problems?

On the basis of discussion or discussion, the teacher revealed:

Consistent footwork (setting, arranging, solving and answering); There is a difference in essence. (See the table below) The application of one-dimensional linear inequality and two-dimensional linear equations.