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

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

Part One: Learning Objectives

1. Understand the meaning of rational number addition and the rationality of the rational number addition rule.

2. Be able to use this rule to accurately perform the addition operation of rational numbers. (Key point)

3. Experience the process of exploring the rules of addition of rational numbers, and understand and master the rules of addition of rational numbers. (Difficulty)

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

Situation introduction

The animal kingdom holds the Olympic Games, and the ant serves as the torch bearer. For the first time, it runs one unit in the positive direction from the origin on the number axis, and then runs one unit in the negative direction. Where is the ant after two movements? How to list the equation?

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

Addition rules for rational numbers

collaborative inquiry

Give it a try: Use the example above to do the math

8+(-8),(-3.5)+(+3.5)

What are the results of these two equations?

(+1) +(-1)＝0

8+(-8)=0

(-3.5)+(+3.5)＝0

Thinking: Observe the characteristics and results of each addend in the above calculation, what do you find?

Think: Is there any other way you can explain the addition of rational numbers? Discuss in groups and use your method to explain the results of the above five calculations.

Summary

Rational number addition rule

(1) Add two numbers with the same sign, the result will have the same sign, and add the absolute values.

(2) When two numbers with different signs are added, the result takes the sign of the addend with the larger absolute value, and subtracts the larger absolute value from the smaller absolute value. The addition of two numbers that are opposites of each other gives 0.

(3) If you add a number to 0, you still get this number.

Applications of rational number addition

Example 2 In a football round robin, the red team beat the yellow team 4:1, the yellow team beat the blue team 1:0, and the blue team beat the red team 1:0. Calculate the goal difference of each team.

Solution: The total number of goals scored by each team is recorded as a positive number, and the total number of goals conceded is recorded as a negative number. The sum of these two numbers is the goal difference of the team.

In the three games, the red team scored 4 goals and conceded 2 goals, with a goal difference of

(+4)+(-2)＝+(4-2)＝2

The Yellow team scored a total of 2 goals and conceded 4 goals, with a goal difference of

(+2)+(-4)=-(4-2)=-2

Basketball scored ( ) goals, conceded ( ) goals, and the goal difference was ( ).

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

1. Calculate:

(1)(-0.6)+(-2.7); (2)3.7+(-8.4);

(3)(-0.6)+3; (4)3.22+1.78;

(5)7+(-3.3); (6)(-1.9)+(-0.11);

(7)(-9.18)+6.18; (8)4.2+(-6.7).

2. Merck, a stockholder, bought 1,000 shares of a company's stock at the closing price of 67 yuan last Friday. The following table shows the daily rise and fall of the stock during this week:

(1) How much is each share at the closing price on Wednesday?

(2) What is the highest price per share this week? What is the lowest price?

Solution: (2) Monday: 67+4=71 yuan,

Tuesday: 71+4.5=75.5 yuan,

Wednesday: 75.5 + (-1) = 74.5 yuan,

Thursday: 74.5 + (-2.5) = 72 yuan,

Friday: 72＋(-6)=66 yuan,

∴The highest price per share this week was 75.5 yuan, and the lowest price was 66 yuan.

Addition of rational numbers PPT, Part 5: Class summary

Addition rules for rational numbers:

Same sign Same sign Addition

Different signs (absolute values ​​are not equal)

Take the sign of the addend with the larger absolute value

Subtract

Different signs (opposites of each other)

The result is 0

Add to 0

Still this number

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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.

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Update Time: 2024-11-23

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