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Three students are taller. As a result, Xiaojun is 1 / 12 meters shorter than Xiaoming and 1 / 20 meters higher than Xiaofang. How many meters is the tallest one higher than the shortest one
Because Xiaojun is one twelfth of a meter shorter than Xiaoming and one tenth of a meter higher than Xiaofang, the difference between Xiaojun and Xiaofang is just one twelfth plus one twentieth, which is two fifths
Xiao Ming is 5 / 7 meters tall, 20 / 1 meters shorter than Xiao Li, and Xiao Jun is 50 / 1 meters shorter than Xiao Li. How tall is Xiao Jun?
Seven fifths minus one twentieth minus one fifty
Xiaoming is 1.40 meters tall. Xiaojun is 110 meters higher than Xiaoming. Xiaoqiang is 110 meters higher than Xiaoming______ Mi, Xiaoqiang's height______ Rice
1.40 × (1 + 110), = 1.40 × 1110, = 1.54 (m), a: Xiaojun's height is 1.54 m, Xiaoqiang's height is 1.54 m, so the answer is: 1.54, 1.54
If both a and B are real numbers greater than zero, please judge:
The size relationship between (root a + root b) / root 2 and root (a + b)
[(root a + root b) / root 2] ^ 2 - [root (a + b)] ^ 2
=(a+b+2√ab)/2-(a+b)
=-(a+b-2√ab)/2
=-(√a-√b)^2/2
≤0
So,
[(radical a + radical b) / radical 2] ^ 2 ≤ [radical (a + b)] ^ 2
(radical a + radical b) / radical 2 ≤ radical (a + b)
The distance between a and B is 360 km. The bus and the truck start from a to B at the same time. The bus runs 60 km per hour and the truck 40 km per hour. After arriving at B, the bus stops for 0.5 hours and returns to a at the same speed. How many hours after starting from a?
Answer to fortune 30 in 30 minutes!
（360×2+60×0.5）÷（60+40）
=750÷100
=7.5 hours
Given a = (3,4), and a · B = 10, then the number of projections of B in a direction is equal to?
What is the concept of projection
Projective, the perpendicular foot Q obtained by drawing a perpendicular line from point P to line (plane) a is called the orthographic projection of point P on line (plane) a
Vector projection, let the unit vector E be the direction vector of the straight line m, and let the vector AB = a, make the projection a 'of point a on the straight line m, and make the projection B' of point B on the straight line m, then the vector a'B 'is called the positive projection of AB on the straight line m or in the direction of vector E, which is called projection for short. The module of vector a'B' | a'B '| = | ab ·| cos 〈 a, e 〉| = | a · e |
a=(3,4),==>|a|=5.
A. B = | a | B | cos 〈 a, B 〉 = = > | B | cos 〈 a, B 〉 = 2
Therefore, the number of projections of B in direction a = | B '| = | B | ·| cos 〈 a, B 〉| = 2
Team a and team B work together to build a 240 km long road. Team a works alone for 10 days, and team B works alone for 15 days,
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Team a and team B jointly build a 240 kilometer long road. Team a will finish it in 10 days and team B will finish it in 15 days. If the two teams work together, how many days can they finish it? (answer in two ways)
According to the meaning of the question, a repairs 240 ／ 10 = 24 kilometers a day, B repairs 240 ／ 15 = 16 kilometers a day, a and B cooperate to repair 24 + 16 = 40 kilometers a day
Given a square + b square = 40, ab = 12, find the value of a square - b square
a²+b²+2ab=40+24
（a+b)²=64
a²+b²-2ab=40-24
（a-b)²=16
a²-b²=(a+b)(a-b)
So [A & sup2-b & sup2] & sup2 = 64 * 16
A & sup2-b & sup2 = 32 or - 32
The distance between the two places is 100 km. The two cars leave from the two places at the same time and meet in 4 / 5 hours. The speed ratio of car a and car B is 3:2. Car a travels every hour and car B runs every hour
Ask for the formula, not the final answer
Vtotal = 100 / (4 / 5) = 125 (km / h)
V a = 125 * 3 / 5 = 75 (km / h)
V b = 125 * 2 / 5 = 50 (km / h)
Answer:
As shown in the figure, in the equilateral triangle ABC, D is the moving point on the edge of ab. take CD as one side, make the equilateral triangle EDC upward, and connect AE. The following are proved: (1) ace ≌ BCD; (2) AE ∥ BC
It is proved that: (1) the ∵ ABC and ∵ EDC are equilateral triangles, ∵ ACB = ∠ DCE = 60 °, AC = BC, DC = EC, and ∵ BCD = ∠ ACB - ∠ ACD, ∵ ace = ∠ DCE - ∠ ACD, ? BCD = ∠ ace. ≌ △ ace ≌ △ BCD, and ? ABC = ∠ CAE = 60 °, and ? ACB = 60 °, and ∫ CAE = ∠ ACB, ≌ AE ‖ BC
RELATED INFORMATIONS
- 1. Xiaoming and I want to buy a toy car for 28 yuan, so each person should pay 14 yuan, but I have no money, so I borrow 14 yuan from Xiaohua (Xiaohua also wants it, so he agrees to buy a toy car with me for 7 yuan, but Xiaohua gives it all). How much money should I pay back to Xiaohua?
- 2. Xiaoming Xiaobai goes to buy books. Xiaobai borrows money to buy Xiaoming a dictionary. He has 20 yuan left. Xiaoming borrows money to buy Xiaobai famous books I have 4 yuan left. The price of the famous book is three times that of the dictionary. How much are the two books? No XY. Please use the formula (such as (59 + 3) / 5) and the equation Two kinds of formulas (the price of dictionary and the price of famous works)
- 3. There are 10 required answers, and 20 points will be deducted for one wrong answer. Xiao Ming got 40 points. How many wrong questions did Xiao Ming get? How many questions can be answered correctly? Can right and wrong be restored? Xiao Ming gets 40 points, and how many questions can Xiao Ming answer correctly? Xiao Ming should get 80 points if he answers 8 questions correctly, but Xiao Ming gets 40 points
- 4. Xiao Ming, Xiao Hong and Xiao Fang did 72 math problems. Xiao Ming did 8 more than Xiao Hong, and Xiao Fang did 12 less than Xiao Ming and Xiao Hong What's wrong with each other?
- 5. Every page of Xiaoming's diary is numbered with 981 numbers from 0 to 9. Please figure out how many pages there are in Xiaoming's diary! Every page of Xiaoming's diary is numbered. He uses 981 numbers from 0 to 9. How many pages does Xiaoming's diary have? There should be a process and answer questions
- 6. There are 15 questions in total, 8 points for one right question, 4 points for one wrong question and 72 points for Xiao Ming. How many questions have you answered correctly? You can't use negative numbers or X to express, the simpler the better
- 7. The mathematics interest group held a test. There were 15 questions in the whole paper. It was stipulated that 8 points would be deducted for each right question and 4 points would be deducted for each wrong question. Xiaoying got 72 points in total, and she did it right______ Question
- 8. Baidu asked Xiaoming to do math problems, each right one plus 10 points, do a wrong deduction of 5 points, a total of 10 questions, the final 55 points ask right and wrong each several questions extra urgent
- 9. Master Wang made a light box with 78.5 square centimeters of openings in the middle of the top and bottom. How much colored paper did he use? 20cm in diameter
- 10. The circumference of a cuboid is 80cm, and the ratio of length to width is 4:1. What's the area of the cuboid? Tao Jie and Jiang Tao travel from a to B at the same time, and their speed ratio is 4:3. Tao Jie travels 20 kilometers per hour, and Jiang Tao travels how many kilometers per hour?
- 11. Xiaoming is 142 cm tall, a cm shorter than Xiaohua, and Xiaohua is () cm tall
- 12. Xiaoming's height is 112 cm higher than Xiaojun's, and Xiaojun's height is 12 cm shorter than Xiaoming's______ ．
- 13. Xiao Gang is 140 cm tall. Xiao Gang is 27 times higher than Xiao Ming. How many cm is Xiao Ming?
- 14. Xiaogang and Xiaoqiang practice running on the 400 meter circular track. Their speed is 200 meters per minute and 160 meters per minute respectively
- 15. Xiao Gang used to have some pictures. He took out half of them and gave them to his younger brother. Later he bought 18 more. At this time, there were 47 pictures. How many pictures did he have?
- 16. Xiaoming starts from a at 8 a.m. and goes to B at 20 kilometers per hour. 15 minutes later, Xiaogang starts from a and goes to B at 6 kilometers per hour In B, Xiao Ming takes a 60 minute rest in B and then returns to A. on the way back, he meets Xiao Gang who starts from A. at this time, they are 2 kilometers away from B. find the distance between a and B
- 17. Xiaoming starts from a at 8 a.m. and goes to B at 20 kilometers per hour. 15 minutes later, Xiaogang starts from a and goes to B at 16 kilometers per hour In B, Xiao Ming takes a 60 minute rest in B and then returns to A. on the way back, he meets Xiao Gang from A. at this time, they are 2 kilometers away from B. find the distance between a and B
- 18. Xiaohong and Xiaoqiang start from home at the same time. Xiaohong walks 52 meters per minute and Xiaoqiang 70 meters per minute. They meet at a on the way. If Xiaohong starts 4 minutes ahead of schedule and Xiaoqiang walks 90 meters per minute, they still meet at a. how many meters are Xiaohong and Xiaoqiang's homes apart?
- 19. Xiao Li and Xiao Gang are 900 meters away from home. They start from home at the same time. Xiao Li walks 60 meters every minute and Xiao Gang walks 90 meters every minute. A few minutes later, they meet?
- 20. The water in children's body accounts for about 45% of their body weight. Xiaoming has 28 kg of water in his body. How many kg is Xiaoming's weight?