"Subtraction of Rational Numbers" Rational numbers and their operations PPT download

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"Subtraction of Rational Numbers" Rational numbers and their operations PPT download

Part One: Review of Old Knowledge

Rational number addition rule

To add two numbers with the same sign, the absolute value is added without changing the sign;

Different signs add "big" and subtract "small", and the signs follow "big";

On the contrary, when summing two numbers, remember that the result is zero;

The added value to zero remains unchanged, and the observed characteristics must be remembered.

One observation, two determination, three summation

Subtraction of rational numbers PPT, part 2: exploration of new knowledge

calculate:

(1)15+(-6) (2)19+(-3) (3)12+0

(4)(-10)+7(5)10+3

Think about it and do it:

1. Assume that the temperature in the urban area on a certain day is 11°C.

(1) If it drops by 6°C in the evening, what is the temperature in the evening? How is it calculated?

(2) If the temperature drops by 15°C in the evening, what is the temperature in the evening? How do you calculate it? Communicate with peers.

2. According to the weather station forecast: the highest temperature in Urumqi is 4 ℃ and the lowest temperature is -3 ℃. What is the temperature difference in the city today? How do you calculate it?

Compare and discuss:

First, ask students to calculate the following two equations:

(1) 11 + ( –15); (2) 4 + 3

Then compare the following formulas, can you find the rules? Discuss in small groups.

Calculate the following equations:

15 - 6 = ___

19 - 3 = ___

12 - 0 = ___

8 - (-3) = ___

10 - (-3) = ___

Rule: Subtracting a number and adding its opposite number will result in the same result.

After reorganizing the above text, we get the subtraction rule of rational numbers that we learned today:

Subtracting a number is equal to adding its opposite.

Do it:

Ask students to write down the calculations of Knowledge Skill 1 on page 42 of the textbook based on this rule and see who can do it faster and better.

Subtraction of rational numbers PPT, part 3: application of knowledge

Example 1 Calculate the following equations:

(1) 9 – ( – 5); (2) ( – 3) – 1

(3) 0 – 8; (4) ( – 5) – 0

Example 2. The highest mountain in the world is Mount Everest, with an altitude of 8844 meters, and the altitude of the Turpan Basin is -155 meters. What is the height difference between the two places?

Solution: 8844-(-155)

=8844+155

＝8999 (meter)

Therefore, the height difference between the two places is 8999 meters.

Example 3: The whole class is divided into five groups to play the game. Each group is basically divided into 100 points. 50 points are added for each correct answer and 50 points are deducted for each incorrect answer. At the end of the game, the scores of each group are as follows:

(1) How many points does the first place exceed the second place?

(2) How many points does the first place exceed the fifth place?

Subtraction of rational numbers PPT, Part 4: Consolidation exercises

1. fill in the blank

⑴-9＋( )＝16; ⑵42＋( )＝-25;

⑶( )-(-18)＝35; ⑷( )-87＝-21

2. calculate

3. The following table shows the time differences between several foreign cities and Beijing (the number with a positive sign indicates the time difference that is earlier than Beijing time at the same time)

city ​​time difference

New York -13

Paris -7

Tokyo +1

Chicago -14

(1) Beijing time is now 7:00, so what is the current time in New York?

(2) Xiao Ming wants to call his aunt in Paris. Do you think it’s appropriate?

Subtraction of rational numbers PPT, Part 5: Class summary

Rule for subtraction of rational numbers:

Subtracting a number is equal to adding its opposite.

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

"Subtraction of Rational Numbers" Rational numbers and their operations PPT:

"Subtraction of Rational Numbers" Rational Numbers and Their Operations PPT Part 1 Content: Knowledge Points Basic Knowledge Point 1 Subtraction Operation of Rational Numbers 1. The following calculations are correct (D) A.-1-1=0 B.7-(-7) =0 C.-3-( +3 )=6 D.0-( -4 )=4 2. The following statements..

"Subtraction of Rational Numbers" Rational Numbers PPT Courseware (Lesson 2):

"Subtraction of Rational Numbers" Rational Numbers PPT Courseware (Lesson 2) Part One: Learning Objectives: Understand the meaning of unifying the addition and subtraction of rational numbers into addition, and be able to skillfully perform mixed operations of addition and subtraction of rational numbers (key points); Be able to use the addition of rational numbers Subtraction solves simple...

"Subtraction of Rational Numbers" Rational Numbers PPT Courseware (Lesson 1):

"Subtraction of Rational Numbers" Rational Numbers PPT Courseware (Lesson 1) Part One: Learning Objectives: Understand and master the subtraction rules of rational numbers (key points); Be able to perform subtraction operations of rational numbers (difficulty); Be able to convert the subtraction operations of rational numbers into addition operations. .....

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Update Time: 2024-09-08

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