![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
Exploration on the expansion of 94 pages in the experimental textbook of compulsory education curriculum standard
Let the length of the train be x meters
Tenth x = twentieth x + 300
x=300
Beijing Normal University Edition mathematics book of Grade 7 Volume 1 237
Children's shoes:
Do your homework independently
If you have any difficulty, you can send the question
It's better not to ask for answers directly
You think so
Who is good at helping others with their homework?
What's more, I don't know what you're talking about
Beijing Normal University (-64)+17+(-23)+68 （-52）+241+（-74）+2 41+（-23）+（-31）+0 (- 26) + 52 + 16 + (- 72),
(-64)+17+(-23)+68
=-64+17-23+68
=-47-23+68
=-70+68
=-2
(-52）+241+（-74）+2
=-52+241-74+2
=189-74+2
=115+2
=117
41+（-23）+（-31）+0
=41-23-31+0
=18-31+0
=-13
（-26）+52+16+（-72）
=-26+52+16-72
=26+16-72
=42-72
=-30
Answers to classroom exercises of p139 mathematics book Volume 1, Grade 7, Beijing Normal University Edition (need process)
De denominator 3 (3-x) = 2 (x + 4)
Remove bracket 9-3X = 2x + 8
Shift - 3x-2x = 8-9
Merge category - 5x = - 1
The conversion coefficient is 1 x = 1 / 5
De denominator 7 (x + 1) = 3 (2x-3)
Remove brackets 7x + 7 = 6x-9
Shift 7x-6x = - 9-7
The conversion coefficient is 1 x = - 16
(3) De denominator 4 (x + 2) = 5x
Remove bracket 4x + 8 = 5x
Shift 4x-5x = - 8
Merge category - x = - 8
The conversion coefficient is 1 x = 8
De denominator 3 (x + 1) = 4 (x-1)
Remove bracket 3x + 3 = 4x-4
Shift 3x-4x = - 4-3
Merge category - x = - 7
The conversion coefficient is 1 x = 7
De denominator 4 (2x-1) = 3 (x + 2) - 12
Remove bracket 8x-4 = 3x + 6-12
The shift is 8x-3x = 6-12 + 4
Merge similar items 5x = - 2
The conversion coefficient is 1 x = - 2 / 5
De denominator 5 (x-1) = 20-2 (x + 2)
Remove bracket 5x-5 = 20-2x-4
Shift item 5x + 2x = 20-4 + 5
Merge similar items 7x = 21
The conversion coefficient is 1 x = 3
Beijing Normal University Grade 7 mathematics book exercise 5.4 knowledge and skills
If C is the temperature of centigrade and F is the temperature of Fahrenheit, then the relationship between C and F is C = 5 / 9 (f-32)
Substitute C = 15 into C = 5 / 9 (f-32)
15=5/9（f-32）
Divide both sides by 5 / 9 to get 27 = f-32
The result is f = 59
A: when C = 15 ℃, f = 59 ° F
Beijing Normal University Grade 8 mathematics volume 1
20. Due to the influence of other factors, the price of pork decreased in early April, and the price of pork per kilogram was 2 / 3 of the original price after the reduction. In the middle of April, the price of pork began to rise. After two months, the price of pork was raised to 14.4 yuan per kilogram
How to prove Pythagorean theorem by Pythagoras' method
0
It is said that Pythagoras verified the Pythagorean theorem with the help of two graphs as shown in the figure. Can you tell us the truth?
According to the meaning of the title, the area of the small blank square in the middle of the first figure is C2;
In the second figure, the sum of the areas of the two small squares in the blank is A2 + B2,
∵ they are all equal to the area of a square with side length a + B - the area of a right triangle with four right sides of a and B respectively,
∴a2+b2=c2．
In a right triangle, the square of the hypotenuse is equal to the sum of the squares of the two right sides
Several proofs of Pythagorean theorem
There are more than 220 kinds
The most classic is the Pythagorean diagram
Let: the short side length a, the long side length B and the oblique side length C
a×b÷2×4＋（b－a）×（b－a）＝c×c
The solution is: a × a + B × B = C × C
The area of the four right triangles plus the area of the small square in the middle is equal to the area of the big square
Why is Pythagorean theorem called quotient theorem?
Pythagorean theorem (also called quotient theorem) is a basic geometric theorem, which was discovered by Shanggao as early as Shang Dynasty in China
RELATED INFORMATIONS
- 1. Why is Pythagorean theorem the first mathematical theorem discovered by human beings? When I studied the Pythagorean theorem, I felt that the discovery of this theorem was not simple. Why do many countries say that the Pythagorean theorem is the earliest mathematical theorem they know. Is this accidental or
- 2. Chapter nine arithmetic problems The water surface of a pool is 10 feet square. In the center, there is a reed which is one foot higher than the water surface. If you pull it vertically to the bank, its top just reaches the surface of the bank. Ask the water depth and the length of the reed
- 3. Zuchongzhi also wrote a book called‘
- 4. Find some English stories. Do me a favor. On Wednesday, I have to Hope is some fairy tales in English
- 5. What do you mean by listening? Be simple and clear! Use it in primary school science
- 6. Find 20 Pythagorean theorem to solve more problems!
- 7. The problem of calculating the area of double knobs by integral It seems that θ can't take pi / 4 to pi / 2? When drawing, is the graph in the first quadrant only 0 to pi / 4? So when integrating in polar coordinates, the upper limit of integration is pi / 4, right? And I still don't know whether the angle in polar coordinates is determined by the angle between the X axis and the X axis, and the graphs with angles not in the defined domain will not be drawn Although it seems that the graph is continuous, its value of θ is not continuous, is it? Thank you!
- 8. The definition of Pythagorean theorem, specific
- 9. Chinese mathematicians Who knows? Easy!
- 10. There is a mathematical Pythagorean theorem problem It is known that there are two fishing boats in port B. ship a and ship b set out at the same time. If ship a goes along the direction of 60 degrees north by east at a speed of 8 nautical miles per hour, ship B sails along the direction of 30 degrees south by East with a speed of 9 nautical miles per hour. Two hours later, ship a arrives at Island m and ship B sails to island P. please estimate the distance between island m and island P
- 11. Junior high school mathematics book Volume 1, page 24 exercise (in the inquiry below) 4 problem formula Plus answer!
- 12. 2005x－2007y＝2003 2004x－2006y＝2002 x. How much y
- 13. If the rational number a is greater than the rational number B, then () A. The absolute value of a is greater than that of B B. The absolute value of a is less than that of B C. The opposite number of a is greater than that of B D. The opposite number of a is less than that of B
- 14. The answer to the latest test paper of compulsory education curriculum standard experimental textbook published by people's Education Press I am a teacher, I want to let students read early at the end of the term!
- 15. The Beijing Tianjin Intercity Railway will be put into operation on August 1, 2008. It is estimated that the one-way direct operation time of high-speed train between Beijing and Tianjin will be half an hour. In a test run, the running time of the test train from Beijing to Tianjin is 6 minutes longer than the expected time, and the travel time from Tianjin to Beijing is the same as the expected time The average driving speed is 40 kilometers per hour. What is the average speed from Beijing to Tianjin during the test run?
- 16. On the number axis, an ant starts from the origin and crawls 1 unit length to the right for the first time, then 2 units to the left for the second time, 3 units to the right for the third time, and 4 units to the left for the fourth time, Question: (1) where is the last position of the ant on the number axis? (2) what is the sum of the numbers corresponding to the positions reached after each crawl? (3) how long has the ant crawled
- 17. 1.（10-11）×（11-12）×（12-13）×… ×（99-100）=_____ . 2. - 1 - (- 5 and 1 / 2) × (+ 3 / 11) [main process] 3.2 / 3 × (- 1 / 2) - (- 1 and 1 / 2) × (- 1 and 1 / 3) [main process] 4. Simple calculation: 15 × (- 3 / 5 + 1 / 3) - 24 × (5 / 12-7 / 8) [main process] 5. Using a simple method to calculate: - 8 × (- 13 and 7 / 12) - (- 5) × (- 13 and 7 / 12) + 4 × (- 13 and 7 / 12) [main process] 6. Two kinds of operations are defined as follows: + 0means "+ there is a circle outside" × "means" × there is a circle outside ". For any two rational numbers a, B has: a + ○ B = a + B-2, a ×0b = a · B-2. Find the value of - 4 × (6 + ○ 8)
- 18. According to the book classification of Xinhua Bookstore, understand the classification of society
- 19. Xiaoming and Xiaogang go to the library to borrow books. Xiaoming goes once every nine days and Xiaogang goes once every six days. If they meet in the library on February 2, what day will they meet again in the library?
- 20. On June 1, I went to Xinhua Bookstore to buy a book. Walking into the bookstore, it was like walking into the sea of books. I crowded into the crowd and bought a copy of "youth composition guide". I was very happy. At this time, a young pioneer ran over and saw that he was very anxious. He also wanted to buy the book, but the odd number had been sold out. I gave my book to him, and the sales assistant and aunt saw this scene, Laugh. (enlarge it into a composition of more than 400 words) On June 1, I went to Xinhua Bookstore to buy a book. Walking into the bookstore, it was like walking into a sea of books. I crowded into the crowd and bought a copy of "youth composition guide". I was very happy. At this time, a young pioneer ran over and saw that he was very anxious. He wanted to buy the book, but the book was sold out. I gave my book to him, and the shop assistant and aunt saw this scene, Laugh. (according to the above story content, please expand reasonable imagination, and write things in detail. If you can't write more than 400 words, you can also make an outline)!