"Addition and Subtraction of Rational Numbers" PPT Courseware 2

Description

"Addition and Subtraction of Rational Numbers" PPT Courseware 2

Knowledge and skills

1. Be proficient in the addition and subtraction rules of rational numbers.

2. Be able to perform mixed operations of addition and subtraction of rational numbers to cultivate students' calculation ability.

Process and Method

--Experience the transformation ideas in mathematics through learning the mixed operations of addition and subtraction of rational numbers.

Emotional attitudes and values

--By learning the mixed operations of addition and subtraction of rational numbers, students can develop serious and meticulous calculation habits.

Teaching focus

1. Mixed operations of addition and subtraction of rational numbers.

2. Unify addition and subtraction into the form of addition without brackets and read it out.

Create situations and introduce new lessons

One winter morning, the temperature was only -7℃. At noon, the temperature rose by 11℃, and then dropped by 9℃ at midnight. What was the temperature at midnight?

Please ask students to self-study textbook P24-25 and complete the self-study tutorial. I believe everyone will understand quickly!

Key points of perception one

After the introduction of opposite numbers, the mixed operations of addition and subtraction can be unified into addition operations, that is, a+b-c=a+b+(-c).

Key points of perception 2

a-(+b)-(-c) is written as a-b+c without the sum of brackets. It has two reading methods: the first reading is the sum of a, negative b, and c; the second reading is a minus b plus c.

Addition and subtraction are unified into addition

When the mixed operations of addition and subtraction are uniformly written as addition operations, change the minus sign to a plus sign, and at the same time change the subsequent subtrahend into the opposite of the original number, and finally write it in the form of a sum with the plus sign omitted.

Correspondence exercises

1. 36-5-7+4 is pronounced as ____________, or as ____________.

2. Use the formula to express: 40 minus 35 plus 12 minus minus 16 minus 4: 40-35+12-(-16)-4.

3. Write the following equations as sums omitting the plus sign.

(1)(-7)-(-8)+(-2)-(-12)+(+3)=-7+8-2+12+3;

(2)(-6.3)-(-7.5)-(-2)+(-1.2)=-6.3+7.5+2-1.2;

(3)0-(+8)-(-2.5)-(+5)+(-1.5) = 0-8+2.5-5-1.5;

(4)(-3)+(-4)-(-11)+(-11)-(-19) =-3-4+11-11+19;

Mixed operations of addition and subtraction of rational numbers

When performing mixed operations of addition and subtraction of rational numbers, pay attention to the order of operations, counting from left to right. Use the law of addition to make operations simple. The principle is: combine positive numbers and negative numbers respectively; combine fractions with the same denominator or fractions that are easier to divide. ; Combine two numbers that are opposites of each other; combine two numbers whose sum is an integer.

Application of rational number addition and subtraction operations in practical problems

A motorcycle factory plans to produce 250 motorcycles per day this week. Since workers take turns to take turns, the number of people working every day is not necessarily the same. The actual daily production volume compared with the plan is as follows (the number of increased vehicles is positive, and the number of reduced vehicles is positive. number is negative):

(1) According to the records, how many motorcycles were produced on Saturday this week?

(2) How many units has the total production volume decreased this week compared with the planned volume?

Analysis: (1) 250+(-9)=241 (vehicles), that is, 241 vehicles were produced this Saturday.

(2)(-5)+7+(-3)+4+10+(-9)+(-24)

=-5+7-3+10-9-24

=(-5-3-9-24)+(7+4+10)

=－41+21=－20.

Therefore, the total production this week is reduced by 20 units compared with the planned production volume.

Class summary

1. Addition and subtraction are unified into addition;

2. Mixed operations of addition and subtraction of rational numbers;

3. Practical applications of addition and subtraction of rational numbers;

Keywords: Teaching courseware for addition and subtraction of rational numbers, Qingdao edition seventh grade mathematics volume PPT courseware download, seventh grade mathematics slide courseware download, addition and subtraction of rational numbers PPT courseware download, .PPT format;

For more information about the PPT courseware "Addition and Subtraction of Rational Numbers", please click the Addition and Subtraction of Rational Numbers ppt tag.

"Addition and Subtraction of Rational Numbers" PPT courseware:

"Addition and Subtraction of Rational Numbers" PPT courseware Learning objectives: 1. Experience the process of exploring the addition of rational numbers, realize the significance of addition of rational numbers, and understand the rules of addition of rational numbers. 2. Be able to skillfully apply rules to perform addition operations of rational numbers. 3. By utilizing data...

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Update Time: 2024-10-03

This template belongs to Mathematics courseware Qingdao Edition Seventh Grade Mathematics Volume 1 industry PPT template

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