1. There is a fraction. If the numerator and denominator are all increased by 1, the fraction becomes 1 / 2. If the numerator and denominator are all decreased by 1, the fraction becomes 2 / 5. Find the fraction 2、1/1×2+1/2×3+1/3×4+…… +What is the value of 1 / 9 × 10? 3. To build a section of highway, team a will build 10 fields separately, and team B will build 12 days separately. If team B builds 4 days first, and the rest team a will build alone, how many days will it take? 4. There are 310 people in two workshops. Three fifths of the people in workshop a are equal to two fifths of the people in workshop B. how many people are there in workshop a and workshop B? 5. It takes 15 hours for car a to drive from city a to city B, and 12 hours for car B to drive from city B to city A. after a few hours, can the two cars meet? 6. Four cows and three horses eat 90 kg of grass per day, eight cows and two horses eat 140 kg of grass per day. How many kg of grass per cow and horse per day? 7. A student participated in the test and found that if he got 97 in this test, his average score was 90. If he got 73, he was puzzled that his average score was 87. How many tests did the student take, including this test? 8. Party A and Party B have several yuan in total, of which Party A accounts for 60%. If Party B gives Party A 15 yuan, the remaining money of Party B is 3 yuan less than 25% of the total money. How much yuan do Party A and Party B have in total? 9. 2 / 3 of the number a is equal to 1 / 5 of the number B. how much less is the number a than the number B? 10. If a commodity is sold at 80% of the price, it can make a profit of 20%. If it is sold at the price, what percentage can it make? The most important problem is that children say that there are only unknowns in learning. Only x and Y haven't been learned yet. It seems that x alone can't be used

1. There is a fraction. If the numerator and denominator are all increased by 1, the fraction becomes 1 / 2. If the numerator and denominator are all decreased by 1, the fraction becomes 2 / 5. Find the fraction 2、1/1×2+1/2×3+1/3×4+…… +What is the value of 1 / 9 × 10? 3. To build a section of highway, team a will build 10 fields separately, and team B will build 12 days separately. If team B builds 4 days first, and the rest team a will build alone, how many days will it take? 4. There are 310 people in two workshops. Three fifths of the people in workshop a are equal to two fifths of the people in workshop B. how many people are there in workshop a and workshop B? 5. It takes 15 hours for car a to drive from city a to city B, and 12 hours for car B to drive from city B to city A. after a few hours, can the two cars meet? 6. Four cows and three horses eat 90 kg of grass per day, eight cows and two horses eat 140 kg of grass per day. How many kg of grass per cow and horse per day? 7. A student participated in the test and found that if he got 97 in this test, his average score was 90. If he got 73, he was puzzled that his average score was 87. How many tests did the student take, including this test? 8. Party A and Party B have several yuan in total, of which Party A accounts for 60%. If Party B gives Party A 15 yuan, the remaining money of Party B is 3 yuan less than 25% of the total money. How much yuan do Party A and Party B have in total? 9. 2 / 3 of the number a is equal to 1 / 5 of the number B. how much less is the number a than the number B? 10. If a commodity is sold at 80% of the price, it can make a profit of 20%. If it is sold at the price, what percentage can it make? The most important problem is that children say that there are only unknowns in learning. Only x and Y haven't been learned yet. It seems that x alone can't be used

1. Let the numerator be x and the denominator be y. from the meaning of the question, we can get: (1 + x) / (1 + y) = 1 / 2 (x-1) / (Y-1) = 2 / 5, and solve the equations. We can get x = 5, y = 11. So the fraction is 5 / 112. The original formula = 1 / 2 * 1 + 1 / 2 * 1 / 3 + 1 / 3 * 1 / 4 + +1/9*1/10=1/2+1/3(1/2+1/4)+…… +1/9(1/8+1/10)=1/2+1...

Xiaoming and Xiaohua ride bicycles from a and B at the same time. After meeting for 25 minutes, they still go at the same speed. When they arrive at each other's starting point, they return immediately. How many minutes does it take Xiaohua from B to a from a to meet Xiaoming for the second time?

Obviously, when Xiaohua arrives at a, Xiaoming has already walked back from point B, the whole distance is (25-20) / 25 = 1 / 5, so we can take Xiaohua's speed as 1, Xiaoming's speed is 1 + 1 / 5, that's simple
Xiaohua takes 25 * [1 + (25-20) / 25] = 30 minutes for the distance Xiaoming takes in 25 minutes
25 * [1 + (25-20) / 25] + 25 = 55 minutes
1+1/5=1.2
55/1.2=45.833333
It takes Xiaohua 55 minutes and Xiaoming 45.83333 minutes

1. A pool is equipped with a water inlet pipe and a drainage pipe. The pool can be filled by opening the water inlet pipe for 40 minutes, and the full pool can be drained by opening the drainage pipe for 1 hour. Master Wang has to drain one-third of the original dirty water into the pool, and then put it into the half pool of clean water. But when he put in the clean water, he forgot to close the drainage pipe, so how many minutes will it take to fill the half pool of clean water?
2. In a rectangular container, there is 12cm deep water. Due to the sudden change of weather, there is a layer of ice on it, and the thickness of ice is 3.6cm. It is known that the volume of water freezing will increase by one part. How many cm is the water depth under the ice?
3. There are 152 students in the fifth grade of a primary school. One of the boys and five girls are selected to watch the model air show. The number of other boys and girls is just the same. How many boys and girls are there in the fifth grade?
4. Someone came to the well with a rope to draw water. He tied the rope into a single strand, but the rope was still 7 meters long. He tied the rope into two strands, but the rope was still 7 meters short. Q: how long is the rope? How deep is the wellhead from the water?
5. There is a pile of candy, of which milk candy accounts for 9 / 20. After adding 16 pieces of fruit candy, milk candy only accounts for 1 / 4. How many pieces of milk candy are there?
6. For a job, Party A will do it in 8 days and Party B will do it in 10 days. How many days can the two teams cooperate to complete it?
7. For a project, Party A will complete it in 12 hours and Party B will complete it in 15 hours. If two people cooperate for 2 hours and Party B will do it alone, how many hours will it take to complete it?
8. For a manuscript, it takes 12 hours for a typist and B to type together, 20 hours for a typist to type alone, and how many hours for B typist to type alone?
9. A local train and an express train leave from station a and station B at the same time. After meeting for 20 hours, it will take 30 hours for the local train to arrive at station B, and how many hours for the express train to arrive at station a?
10. Fill in the appropriate number in the brackets according to the rule
（1）12,4,4/3,（ ）,（ ）
（2） 8,1,（ ）,（ ）,512

1. The filling speed of the inlet pipe is 1 / 40 in 40 minutes, and that of the drain pipe is 1 / 60 in 60 minutes. The half filling time is 1 / 2 (1 / 40-1 / 60)
2. The thickness of water to ice is increased by one part, which should be one tenth. Therefore, the 3.6cm ice is composed of 3.6 / 1.1cm water, and the remaining water is 12-3.6 △ 1.1cm ice
There are x male students, so x-0.1 x = 152-x-5
4. Let the rope length x, well depth y, X-Y = 7, Y-X △ 2 = 7, x = 28, y = 21
5. Suppose that the original x candy, (x + 16) × 1 / 4 = x × 9 / 20, and the milk candy is x × 9 / 20, which is 9 pieces of milk candy
6. Party A's speed is 1 / 8, Party B's speed is 1 / 10, and Party A's cooperation speed is 1 / 8 + 1 / 10, so the time required is 1 / 8 + 1 / 10, which is 40 / 9 days
7. Cooperation speed (1 / 12 + 1 / 15), 2 × (1 / 12 + 1 / 15) for 2 hours, 1-2 × (1 / 12 + 1 / 15) for 1-2 × (1 / 12 + 1 / 15), 12 hours for Party B to sit alone
8, cooperation speed 1 / 12, a speed 1 / 20, so B speed 1 / 12-1 / 20 is 1 / 30, so B needs 30 hours
9, 20 hours after the meeting, the slow train takes 30 hours to arrive. Knowing that the slow train takes 50 hours to complete the whole journey, and the fast train takes 20 hours to walk, the slow train takes 30 hours, so the speed is 1.5 times of the slow speed, so the slow train takes 20 hours, and the fast train takes 20 △ 1.5 hours, so the result is that the fast train takes 40 / 3 hours to get to station a
10, (1) it can be seen that the latter number is 1 / 3 of the former, so 4 / 9 4 / 27 should be filled in
(2) If it's hard to fill in: 8 is the third power of 2, 1 is the 0 power of 2, 512 is the 9 power of 2, so it should be arranged according to the 3 power of 2, 0 power of 3 power, 6 power of 9 power. Fill in 8 64

The two problems of seeking shadow in the winter vacation homework of grade 6 in 2011

The answer to the second question: 6 / 2 = 3 find out the radius of the small circle. 3 * 3 / 2 = 4.5 find out the area of a triangle in the 1 / 4 circle. Then find out the area of the 1 / 4 circle: 1 / 4 * 3 * 3.14 = 7.065, then 7.065-4.5 = 2.565 find out the area of the blank part in the small circle: 2.565 * 4 = 12.26, then subtract the area of the blank part from the area of the small circle to get the area of the shadow part in the small circle: 28.26-12.26 = 14, Then we can use 14 * 4 = 56 to get the area of all shadow parts is 56
The answer to the first question: the area of the blank part next to the small sector = the area of the large sector + the area of the rectangle - 1 / 4 of the area of the big circle, Then the area of the shadow part = the area of the large sector + the area of the small sector - the blank part beside the small sector = the area of the large sector + the area of the small sector - the area of the large sector + the area of the rectangle - 1 / 4 the area of the big circle = the area of the small sector + the area of the rectangle - 1 / 4 the area of the big circle = 1 / 4 * 3.14 * 2 + 7 * 2 + 1 / 4 * 3.14 * 7 * 7 = 27.605

Page 25 question 1
Five small squares form a Z shape. Can you cut this figure into three parts by only two cuts, which can be put together into a square?

The title of the building

Cut 5 apples equally and give them to 6 children. Each child is given two apples of the same size. Do you know how to cut apples?

Analysis shows that: divide 5 into 3 and add 2, cut each pair of 3 apples in half to get 6 half pieces, cut 2 apples according to the method of 3 equal parts to get 6 13, 1 ﹣ 2 + 1 ﹣ 3 = 56 (pieces)

Celebration
six one
Celebrating June 1
+May I ask: what numbers do Xi, Qing, Liu and Yi represent?
Add: add = 2008

One = 8 celebration = 4 six = 6 joy = 1

There is an open space of 1798m ^ 2 in a residential area. A swimming pool is two times as long as the width. There is a 5-meter-wide open space in front of the swimming pool, and 3M roads are reserved on the other three sides
(1) How long and wide is the swimming pool?
(2) If the swimming pool is 3M deep, tile the bottom and wall of the pool, please calculate the total area of tile?
Note: the swimming pool is in the middle. When the width of the swimming pool is x and the length is 2x, then (x + 6) (2x + 8) = 1798

(1) Let the width of the swimming pool be x meters, then the length is 2x meters. (2x + 2 + 5 + 1) × (x + 2 + 2 + 1 + 1) = 1798, and the solution is: x2 + 10x-875 = 0, and the solution is: X1 = - 35 (not to be omitted), X2 = 25. From x = 25, 2x = 2 × 25 = 50. The length of the swimming pool is 50 meters, and the width is 25 meters. (2) [(25 × 3 + 50 × 3) × 2 + 25 × 50] × 50 = (450 + 1250) × 50 = 1700 × 50 = 85000 (yuan). Answer: the total cost is 85000 yuan

As shown in the figure, the coordinates of points a, B and C are (0, - 1), (0,2), (3,0) respectively. Select a point from the following four points m (3,3), n (3, - 3), P (- 3,0) and Q (- 3,1). If the quadrilateral with a, B, C as its vertex is not a centrosymmetric figure, then the point is ()
A. MB. NC. PD. Q

According to the judgment of parallelogram, if we know that a, B and P can form a parallelogram with three known points, it must be a centrosymmetric figure

It's good to have mathematics. The publishing house is a member of Beijing Science and Technology Press

Every year, there are students who want the answers to their homework. Of course, I have found them on the Internet, but I can tell you that some of them have answers. Eg: 1 after the exercises, it says: see the next issue for the answers. 2. Search the keywords of a certain problem on Baidu. 3. Ask students why some exercises have no answers because they have problems