"Algebraic Formulas" Integers and their addition and subtraction PPT (Lesson 2)

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"Algebraic Formulas" Integers and their addition and subtraction PPT (Lesson 2)

Part One Content: Basic Knowledge Key Points

Knowledge point 1: Substitute directly to find the value of the algebraic expression

1. When m=2, the value of the algebraic formula 1/2(m+8) is equal to (A)

A.5 B.4 C.3 D.2

2. When a=-1, b=2/5, c=2, when finding the value of the algebraic expression a2bc+b2+1, which of the following substitution procedures is correct (C)

A.-12×2/5×2+2^2/5+1

B.-12×2/5×2+(2/5)^2+1

C.( -1 )2×2/5×2+(2/5)^2+1

D.( -1 )2×2/5×2+2/5^2 +1

Knowledge point 2: Substitute the whole to find the value of the algebraic expression

3. It is known that 2a-b=3, then the value of the algebraic formula 3b-6a+5 is (A)

A.-4 B.-5 C.-6 D.-7

4. It is known that 3x2+x=1, then the value of the algebraic expression 3/2x2+1/2x-2 is (D)

A.1 B.-1 C.3/2 D.-3/2

Knowledge point 3: Program calculation to find the value of algebraic expression

5. Calculate according to the following program. If the initial input value of x is a positive number and the final output result is 283, then the maximum number of different values ​​of x that meet the condition is (B)

A.6 B.5 C.4 D.3

Algebraic PPT, Part 2: Improvement of Comprehensive Ability

8. When x=1 and x=-1, the value of the algebraic expression x4-5x2+1 (D)

A. are opposites of each other B. are reciprocals of each other

C. Opposite sign D. Equal

9. If a is the largest negative integer, b is the rational number with the smallest absolute value, and c is a natural number whose reciprocal is equal to itself, then the value of the algebraic formula a2017+2018b+c2019 is (D)

A.2017 B.2018 C.2019 D.0

10. In the operation program as shown in the figure, if the value of x is 18 at the beginning, we find that the first output result is 9, the second output result is 12,..., then the 10th output result is for(B)

A.0 B.3 C.5 D.6

11. If when x=2, the value of x4+mx2-n is 6, then when x=-2, the value of x4+mx2-n is (C)

A.-6 B.0 C.6 D.26

12. It is known that |a|=3, b2=16, and |a+b|≠a+b, then the value of the algebraic expression a-b is (A)

A.1 or 7 B.1 or -7

C.-1 or -7 D.±1 or ±7

13. Use a rectangular piece of paper with length a and width b to make a rectangular box without a lid. Let the height of the rectangular box without a lid be c (as shown in the figure, only consider the two right corners of the rectangle. Cut out a square of the same size in each case and a rectangle in the upper left corner). If a=7 cm, b=4 cm, c=1 cm, then the volume of this rectangular box without a lid is 8 cm3.

Algebraic PPT, the third part: Expansion, exploration and breakthrough

17. A clothing factory in our city produces a jacket and a T-shirt. Each jacket is priced at 100 yuan and each T-shirt is priced at 50 yuan. During the promotion period, the manufacturer provided two preferential plans to customers: ① Buy a jacket and get a T-shirt for free; ② Both jackets and T-shirts are paid at 80% of the list price. A customer wants to go to the clothing factory to buy 30 jackets and x T-shirts (x>30).

(1) If the customer purchases according to plan ①, he will need to pay 3,000 yuan for the jacket and 50 (x-30) yuan for the T-shirt.

(Expressed by a formula containing

(2) Given that x=40, please explain through calculation which plan is more cost-effective to purchase?

(3) When x=40, can you give a more economical purchase plan? Try to write down your purchase plan.

Solution: (2) From (1), when x=40,

The cost of purchasing according to plan ①=3000+50×(40-30)=3000+500=3500(yuan);

The cost of purchasing according to plan ②=2400+1600=4000 (yuan).

Therefore, it is more cost-effective to purchase according to plan ①.

(3)Can.

First follow plan ① to get 30 jackets and get 30 T-shirts for free, then follow plan ② to buy 10 T-shirts.

The total cost of this purchase plan is 30×100+10×50×80%=3400 (yuan).

Keywords: Free download of Beijing Normal University Edition seventh-grade mathematics PPT courseware for volume 1, algebraic formula PPT download, integer expressions and their addition and subtraction PPT download, .PPT format;

For more information about the PPT courseware "Integers and their addition and subtraction algebraic expressions", please click the PPT tab of "Integers and their addition and subtraction algebraic expressions".

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Update Time: 2024-10-01

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