"Power of Rational Numbers" PPT courseware 3

Description

"Power of Rational Numbers" PPT courseware 3

teaching objectives

Knowledge and skills

1. Through examples, experience the generation process of the concept of exponentiation;

2. Understand the concepts of exponentiation, power, exponent, and base, and master the representation of exponents and powers;

3. Understand the sign rule of power and be able to perform exponentiation operations of rational numbers;

[Emotional Attitudes and Values] Understand the necessity of exponentiation operations through calculation and representation of problems that students are interested in in life.

Teaching focus: concept and calculation of exponentiation.

Teaching difficulties: concepts such as power, power, base, exponent, and the determination of the sign of the power result.

Create situations and introduce new lessons

Answer the following questions as shown in the picture:

(1) How to calculate the area of ​​a square with side length 7 cm?

(2) How to calculate the volume of a cube with an edge length of 5 cm?

"Variation 1" What is the area of ​​a square with side length a centimeter?

What is the volume of a cube with edge length b cm?

Power of rational numbers

2 ×2 ×2×2 ×2 is recorded as 25

a×a ×… ×a ×a is written as an

The operation of finding the product of n identical factors a is called exponentiation

Discuss

What is the difference between (1)-34 and (-3)4?

-34 is read as: the opposite number of 34, and (-3)4 is read as: -3 to the fourth power; -34=-81, (-3)4=81; the difference between base and exponent.

(2) (2/3) What is the difference between 2 22/3?

Notice:

(1) When writing the power of a negative number, the entire negative number (together with the symbol) must be enclosed in parentheses. This is also a way to identify the base;

(2) When writing the power of a fraction, the entire fraction must be enclosed in parentheses;

(3) A single number can be regarded as a power of the number itself, but we usually omit the exponent 1.

Think about it:

Observing the results of Example 1, can you find any rules in the signs of exponentiation operations?

Sign rules for exponentiation operations

Any power of a positive number is a positive number

Negative numbers raised to even powers are positive numbers, and odd powers raised to negative numbers are negative numbers.

All positive integer powers of 0 are equal to 0

Class summary

What gains and experiences have you gained from studying this class?

1. The meaning of exponentiation

2. Correctly distinguish the base and exponent of a power. When writing a negative number or a power of a fraction, the base must be enclosed in parentheses.

3. Properties of power: Any power of a positive number is a positive number; odd powers of a negative number are negative numbers, and even powers of a negative number are positive numbers.

(Any number raised to an even power is nonnegative.) All positive integer powers of 0 are equal to 0.

Homework

(Required questions) Page 63 Exercise 3 questions.

Page 65, Questions 1 and 2 of Group A.

(Optional question) Do you like to eat ramen? The chef at the ramen restaurant uses a very thick noodle, kneads the two ends together and stretches it, then kneads it again, stretches it again, and repeats this several times, until the very thick noodle is stretched into many thin noodles. How many times can 128 noodles be pulled out after kneading like this?

Keywords: Teaching courseware for exponentiation of rational numbers, Qingdao edition seventh-grade mathematics PPT courseware download, seventh-grade mathematics slide courseware download, PPT courseware download for exponentiation of rational numbers, .PPT format;

For more information about the "Power of Rational Numbers" PPT courseware, please click on the Power of Rational Numbers ppt tab.

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"Power of Rational Numbers" PPT courseware 2:

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Update Time: 2024-10-05

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

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