"Opposite Numbers and Absolute Value" PPT Courseware 2

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"Opposite Numbers and Absolute Value" PPT Courseware 2

learning target:

Learn the meaning of opposite numbers with the help of a number line.

Can find the opposite of a number.

Key points and difficulties in learning:

Focus: The concept of absolute value

Difficulty: Using absolute values ​​to compare the size of two negative numbers

Review the past and learn the new

1: Can you draw a number line and mark the points -5 and 5, -0.5 and 0.5, and 0?

2: What characteristics did you find in the arrangement of these points on the number line?

Observe the two pairs of points A and A′, B and B′ on the number axis. What numbers do they represent? What is their positional relationship?

A B B′ A′

● ● ● ● ● ● ● ● ● ● ●

-5 -4 -3 -2 -1 0 1 2 3 4 5

(1) What are the similarities and differences between numbers-4 and 4? -2.5 and 2.5?

Like -4 and 4, 2.5 and -2.5, etc., two numbers with only different signs are called opposite numbers. The special opposite of 0 is 0.

(2) Can you name two other numbers with this characteristic? And share your ideas with your deskmates.

(3) Generally, a number that is not equal to 0 and its opposite are expressed as points on the number axis. What is the relationship between these two points and the origin?

On the number line, two points representing opposite numbers are located on both sides of the origin and are equidistant from the origin.

(4) What is the distance between the point representing 0 on the number axis and the origin?

On the number axis, the distance between a point representing a number a and the origin is called the absolute value, denoted as �a�.

The absolute values ​​of two numbers that are opposites of each other are equal.

Then: when a>0, �a�=a;

When a=0, �a�=0;

When a<0, �a�=-a.

Compare: -20 or -10, which number has the greater absolute value? What about -3 and -1?

What are their absolute values?

What relationship did you find between the magnitude of two negative numbers and their absolute values?

Two negative numbers, the larger the absolute value, the smaller the negative number.

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For more information about the "Inverse Numbers and Absolute Values" PPT courseware, please click on the "Inverse Numbers and Absolute Values" ppt tag.

"Opposite Numbers and Absolute Value" PPT courseware:

"Opposite Numbers and Absolute Value" PPT courseware Opposite numbers are only two numbers with different signs, which are called mutual opposites. One number is the opposite number of the other number. The opposite number of 0 is 0. Numbers that are mutually opposite numbers have on the number axis What characteristics? Represent opposite numbers on the number line.

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Update Time: 2024-07-31

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

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