"Solving word problems using linear inequalities in one variable" PPT courseware

Description

"Solving word problems using linear inequalities in one variable" PPT courseware

Review the past and learn the new

What are the steps to solve linear inequalities of one variable?

What should we pay attention to when solving problems?

Can you tell me the steps to solve word problems using equations?

Test you. Can you form inequalities?

1. The unit price of a certain product is a yuan, and the total cost of buying 50 such products is not more than 342 yuan, then 50a ≤ 342

2. The purchase price of a certain product is 120 yuan, and there are 15 pieces in total. In order to make the profit not less than 1,000 yuan, what is the minimum price of this product?

Solution: Set the price to at least x yuan

(x-120) ×15≥1000

When solving problems involving inequalities, the key is to correctly list the inequalities. When listing inequalities, you must find the words that express the inequality relationship. In practical application questions, you must be able to analyze the inequality relationship based on the meaning of the question.

Research activity one

A store has a discount sale. An electronic keyboard costs 1,800 yuan each. If it is sold at 20% off the listed price, the profit is still less than 10% of the actual selling price. So within what range should the price of the electronic keyboard be?

Actual selling price - purchase price ≥ 10% of actual selling price

Solution: Suppose the price of each electronic keyboard is x yuan, then one unit is sold

The profit earned by the electronic keyboard is not less than 10%×80%x. According to the meaning of the question, we get

80%ｘ�1800 ≥10%×80%x

Solve for x≥2500

Answer: The price of each electronic keyboard is not less than 2,500 yuan.

Research activity two

The general ticket price for a certain tourist attraction is 30 yuan per person, and the ticket price for groups of 20 people or more is 25 yuan per person.

(1) A total of 18 tourists from a tourist group come to visit the scenic spot. Which method of purchasing tickets do they choose to buy tickets cheaper?

(2) If the group size is less than 20 people, when the number of tourists is, buying a group ticket for 20 people is cheaper than buying a general ticket?

Thinking: Assume the number of people in the team is x people, then purchasing general tickets costs ______ yuan. It costs ______ yuan to purchase group tickets for 20 people

Let me summarize

What are the general steps to use inequalities to build mathematical models to solve practical problems?

①Review the question ②Assume the unknown number ③Series inequalities based on the inequality relationship

④Solve the inequality ⑤Check ⑥Answer

Apply what you learn

Xiaolan plans to spend 27 yuan to buy pens and notebooks. It is known that a pen is 4.5 yuan and a notebook is 3 yuan. If she buys a total of 8 pens and notebooks, and at least one of each type, how many types of pens and notebooks does she have to buy? plan?

Solution: Suppose he can buy x pens, then the number of notebooks is (8-x). According to the meaning of the question, we get

4.5x+3(8-x)≤27

Solve for x≤2

∵X is a positive integer,

∴X=2 or 1

Answer: Xiaolan has 2 purchase plans, ① 2 pens and 6 notebooks, ② 1 pen and 7 notebooks.

learning target:

1. Master a method: master the method of solving practical problems in life by listing linear inequalities in one variable;

2. Understand an idea: Understand the mathematical idea of ​​"classification discussion" in the process of "selecting preferential plans";

3. Experience a process: continue to experience the learning process of independent learning and cooperative inquiry.

basic training

Expressed as an inequality:

(1) The sum of 8 and 2 times y is a positive number;

(2) The sum of x and 5 is not less than 0;

(3) 4 times x is greater than the difference between 3 times x and 7.

Keywords: teaching courseware for solving word problems with linear inequalities in one variable, Qingdao edition eighth grade mathematics volume 2 PPT courseware download, eighth grade mathematics slide courseware download, downloading PPT courseware for solving word problems with linear inequalities in one variable, .PPT format;

For more information about the PPT courseware "Solving Word Problems by Listing First-degree Inequalities in One Variable", please click the "Solving Word Problems by Listing First-degree Inequalities in One Variable" ppt tag.

"Solving word problems using linear inequalities in one variable" PPT courseware 3:

"Solving word problems with linear inequalities in one variable" PPT courseware 3 Scenario introduction A certain town has abundant wind resources. In order to achieve low-carbon and environmental protection, the town decided to develop wind power generation and planned to purchase 10 wind turbines. There are two types of units, AB. Among them, the price of type A is...

"Solving word problems using linear inequalities in one variable" PPT courseware 2:

"Solving word problems with linear equations of one variable" PPT courseware 2 Steps for solving word problems with linear equations of one variable: (1) Review: Review the question, analyze what is known in the question, what is sought, and clarify the relationship between the quantities; (2) Find: Find the word that can express the full meaning of the word question..

File Info

Update Time: 2024-07-30

This template belongs to Mathematics courseware Qingdao Edition Eighth Grade Mathematics Volume 2 industry PPT template

Preview