"Addition of Rational Numbers" Rational Numbers and Their Operations PPT (Lesson 2)

Description

"Addition of Rational Numbers" Rational Numbers and Their Operations PPT (Lesson 2)

Part One: Learning Objectives

1. Be able to summarize the commutative law of addition and the associative law of rational numbers.

2. Flexibly and skillfully use the commutative law of addition and the associative law to simplify operations (key points and difficulties)

Addition of rational numbers PPT, part 2: introducing new lessons

Situation introduction

After learning the addition rules of rational numbers, Xiao Ming, who loves to explore, discovered that (-3) + (-6) is equal to (-6) + (-3), and 8 + (-3) is also equal to (-3) + 8. So he thought: Are the sums of any two addends still equal after exchanging their positions? What do you think, students?

Addition of rational numbers PPT, part 3: teaching new lessons

law of addition

collaborative inquiry

Can you cite some more numbers that are consistent with this conclusion? Give it a try!

Think: What can you discover through the above calculations and comparisons?

In the addition of rational numbers, two numbers are added and the positions of the addends are exchanged and the sum remains unchanged.

Commutative law of addition: a+b=b+a

In the addition of rational numbers, when adding three numbers, add the first two numbers first, or add the last two numbers first, and the sum remains unchanged.

Associative law of addition: (a+b)+c=a+(b+c)

Example 1 Calculation

(1) 16+(-25)+24+(-32) (2) 31 + (-28) + 28 + 69

Group discussion: What characteristics of numbers do you grasp to simplify calculations?

What is the basis?

Three commonly used rules:

1. If there are opposite numbers, you can add the opposite numbers first, and if you can round them up, you can round them up first;

2. If there are numbers with the same denominator, you can first combine and add the numbers with the same denominator;

3. Then combine the positive or negative numbers together and add them up.

Addition of rational numbers PPT, part 4: practice in class

1. Calculate:

(1)23+(-17)+6+(-22);

(2)(-2)+3+1+(-3)+2+(-4).

2. Calculate:

3. There are currently 10 baskets of apples, each basket is based on 30 kilograms. The excess kilograms are recorded as positive numbers, and the insufficient kilograms are recorded as negative numbers. The records are as follows (unit: kilograms):

2, -4, 2.5, 3, -0.5,

1.5, 3, -1, 0, -2.5

How much do these 10 baskets of apples weigh in total?

4. The standard weight of each bag of wheat is 90 kilograms. The weighing records of 10 bags of wheat are as shown in the figure. Compared with the standard weight, how many kilograms does the total of 10 bags of wheat exceed or lack? What is the total weight of 10 bags of wheat?

Addition of rational numbers PPT, Part 5: Class summary

commutative law

a+b=_____

associative law

(a+b)+c=__________

application

Keywords: Beijing Normal University edition seventh-grade mathematics PPT courseware free download, addition of rational numbers PPT download, rational numbers and their operations PPT download, .PPT format;

For more information about the PPT courseware "Rational Numbers and Their Operations: Addition of Rational Numbers", please click on the Rational Numbers and Their Operations PPT Addition of Rational Numbers PPT tag.

"Addition of Rational Numbers" Rational Numbers and Their Operations PPT Courseware (Lesson 2):

"Addition of Rational Numbers" Rational Numbers and Their Operations PPT Courseware (Lesson 2) Part One: Knowledge Points Basic Knowledge Point 1 Operational Law of Addition of Rational Numbers 1. Among the following deformations of exchanging the positions of the addends, the wrong one is (D) A. 30+( -20 )=( -20 )+30 B.(..

"Addition of Rational Numbers" Rational Numbers and Their Operations PPT Courseware (Lesson 1):

"Addition of Rational Numbers" Rational Numbers and Their Operations PPT Courseware (Lesson 1) Part One: Knowledge Points Basic Knowledge Point 1 Addition Rule of Rational Numbers 1. The result of calculating (-3)+(-2) is (B) A. 5 B.-5 C.1 D.-1 2. Perform two numbers with different signs in the following..

"Addition of Rational Numbers" Rational numbers and their operations PPT (Lesson 1):

"Addition of Rational Numbers" Rational Numbers and Their Operations PPT (Lesson 1) Part One Content: Learning Objectives 1. Understand the meaning of addition of rational numbers and the rationality of the addition rule of rational numbers. 2. Be able to use this rule to accurately perform the addition operation of rational numbers. (Key point) 3. Sutra..

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Update Time: 2024-10-17

This template belongs to Mathematics courseware Beijing Normal University Edition Seventh Grade Mathematics Volume 1 industry PPT template

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