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For a pile of peaches, the old monkey took one after eating 1 / 2, the big monkey took one after eating the remaining 1 / 2, and the little monkey took another after eating the remaining 1 / 2, As a result, there is only one left. How many peaches are there in this pile?
Xie Xiaohou's peach before eating = (1 + 1) △ 1 / 2 = 4
Before eating = (4 + 1) △ 1 / 2 = 10
The first number is (10 + 1) △ 1 / 2 = 22
In the arithmetic sequence {an}, the tolerance d = 1, A4 + A17 = 8, then A2 + A4 + A6 + +a20=（ ）
A. 40B. 45C. 50D. 55
a4+a17=2a1+19d=2a1+19=8，∴a20=a1+19d∴a1=-112，a20=a1+19d=272，∴a2+a4+… +A20 = − 92 + 2722 × 10 = 45
Math problem (cubic meter)
A bungalow is 10 meters long, 7 meters wide and 3 meters high. Its four walls and top should be painted (excluding 32 square meters of doors and windows). How many square meters is the painted area?
Use 64 pieces of 1 cubic centimeter small cube wood to quickly assemble a large cube. What's the volume of the large cube? What's its surface area?
3 1 L = () M3
1. (10 + 7) * 3 + 10 * 7-32 = 51 + 70-32 = 121-32 = 89 square meters
2. Volume: 1 * 64 = 64 cubic centimeter surface area: 64 to the third power, the side length is 4 cm 4 * 4 * 6 = 96 square centimeter
3. 0.001 M3
The passenger car and the freight car set out from a and B at the same time and went opposite each other. They met in five hours. After meeting, the passenger car went another three hours to reach B. It is known that the freight car travels 63 thousand per hour
(for detailed explanation, urgently needed!)
How many kilometers are there between a and B? 1. How many kilometers did the truck travel in five hours? 63 × 5 = 315 (km). 2. How many kilometers did the passenger car travel in an hour
The height of a marble figure is twice the height of a person of 50 kg. If the density of marble is 2700 kg / Li
The height of a marble figure is twice that of a person of 50 kg. If the density of the marble is 2700 kg / m3, it can be estimated that the mass of the marble figure is about?
70% of the human body is water, and the density is close to 1kg / DM ^ 3, so the volume of 50kg is close to 50dm ^ 3,
The height of the portrait is twice as high as that of the human. If it is expanded in equal proportion, it means that the volume is 2 ^ 3 = 8 times, 50dm ^ 3 * 8 = 400dm ^ 3 = 0.4m ^ 3,
The mass of the image is 2700kg / m ^ 3 * 0.4m ^ 3 = 1080kg
When x satisfies (), the value of | 1.5x-0.5 | + | 2.5x-0.5 | + | 3.5x-0.5 | + | 4.5x-0.5 | + | 5.5x-0.5 | + | 6.5x-0.5 |
,|1.5x-0.5|+|2.5x-0.5|+|3.5x-0.5|+|4.5x-0.5|+|5.5x-0.5|+|6.5x-0.5|≥ |1.5x-0.5+2.5x-0.5+3.5x-0.5+4.5x-0.5+5.5x-0.5+6.5x-0.5|=|24x-3|
When x = 1 / 8, the value of | 24x-3 | is 0
So when x satisfies (x = 1 / 8), the value of | 1.5x-0.5 | + | 2.5x-0.5 | + | 3.5x-0.5 | + | 4.5x-0.5 | + | 5.5x-0.5 | + | 6.5x-0.5 |
The surface area of a cylinder is 125.6 square centimeters, and the sum of its bottom radius and height is 10 centimeters. What is the volume of the cylinder in cubic centimeters?
R + H = 10 surface area of cylinder s = 2 * 3.14 * r * r + 2 * 3.14 * r * H = 2 * 3.14 * r * (R + H) = 2 * 3.14 * r * 10 = 62.8r = 125.6r = 125.6 / 62.8 = 2cmh = 10-2 = 8cm cylinder volume v = 3.14 * r * r * H = 3.14 * 2 * 2 * 8 = 100.48 (cubic centimeter) answer: cylinder volume is 100.48 cubic centimeter
Two times of a number is exactly equal to the reciprocal of one tenth. What is the number?
1÷1/10÷2=5
A = √ 6 B = √ 3 ∠ a = 45 ° solution triangle
A = √ 2 b = √ 3 ∠ a = 45 ° solution triangle (√ is the root)
1: A = {6} B = {3} a = 45 °} Sina = {2A / Sina = B / SINB} SINB = 1 / 2} B = 30 (B is smaller than a)} C = 180-a-b = 105sinc = sin (60 + 45) = (√ 6 + √ 2) / 4 the same as C = (√ 18 + √ 6) / 22: a = {2 b = {3} a = 45 ° Sina = 2A / Sina = B / SINB} SINB = {3 / 2} B = 60 or B =
If you add a percentage sign to a number, the number will be reduced by 29.7______ ．
29.7 ÷ (1-1%), = 29.7 ÷ 0.99, = 30; answer: the number is originally 30; so the answer is: 30
RELATED INFORMATIONS
- 1. A, B, C and D donate to a disaster area. A's donation is 13% of the total donation of the other three people. B's donation is 15% of the total donation of the other three people. C's donation is 16% of the total donation of the other three people. D's donation is 148 yuan. How much yuan did a donate?
- 2. Equation x / 10 + X + 2 / 15 = 1 It's a one yuan one-time application problem. It's an application problem, not a text problem!
- 3. On the two equations of X, X square-x-2 = 0 and 1 / 2 of X-2 = x + 2 / a have the same solution, then what is a =?
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- 5. (answer with formula and analysis) 1. There are four workshops in a factory. The number of people in the first workshop is one third of the total number of people in the other workshops. The number of people in the second workshop is one fourth of the total number of people in the other workshops. The number of people in the third workshop is one fifth of the total number of people in the other workshops. There are 460 people in the fourth workshop? 2. Grandfather Zhang climbs a mountain every day. It takes 20 minutes to walk every 100 meters up the mountain. It takes 5 minutes to walk every 40 meters down the mountain. Grandfather Zhang always takes a rest in a pavilion one hour after climbing the mountain. He just arrives at the pavilion one hour down the mountain. How many meters does he have to walk every day for exercise?
- 6. Application of equation Some students of a class take part in the community tree planting activities. If there are 7 seedlings, there are 5 lessons left. If each student plants 8 seedlings, there is 1 person who plants one less. How many people take part in the tree planting activities
- 7. Solving practical problems with equations There are two kinds of alcohol with 75% and 45% concentration. To prepare 300 grams of alcohol with 65% alcohol, how many grams should be taken from each of the two kinds of alcohol? What I want is the process of solving the equation, and write out the equivalent relation and reason of the equation!
- 8. The formula of practical problem Calculation formulas related to quadratic equation of one variable Just the formula! Examples are better! do somebody a favour
- 9. The formula of application problem A company selects three people from 152 employees to participate in the year-end friendship competition. Any three of them are required to perform on the stage and choose the best three people combination that can represent the company's image. How many three people groups are there in total? Find the formula!
- 10. Solving practical problems with equations A shop sells two pieces of clothes. For some reason, the one with lower purchase price loses 10 yuan, and the one with higher purchase price makes at least 20% profit, so that the two pieces of clothes will not lose money. What is the purchase price of the one with higher purchase price?
- 11. Two monkeys found a push of peaches. The big monkey ate half and half of the peaches. The little monkey ate the other half and half, and there were two left. How many were there
- 12. The little monkey ate four more peaches than the rest. After another one, he ate three times the rest. How many peaches did the little monkey have?
- 13. The little monkey ate four more peaches than the rest. The little monkey ate one more peach and ate three times the rest. How many peaches does the little monkey have? The little monkey ate four more peaches than the rest. The little monkey ate one more peach and ate three times the rest. How many peaches does the little monkey have? Suppose you eat x peaches for the first time X+X-4=4(X+1)/3 X=8 8 + 8-4 = 12 I want to know that x + x-4 = 4 (x + 1) / 3 What's going on in the text?
- 14. The mother monkey picked a basket of peaches. She asked the little monkey to count how many peaches she had picked. The little monkey counted three peaches in three places. Finally, if there was one more, it would count the more peaches One is thrown aside; it counts five and five, and in the end, there is one more, and it throws one more aside; in the end, it counts seven and seven, and there is one more. It counts three times, but it is still unclear how many peaches there are. Children, do you know how many peaches there are at least in this basket? (the process of seeking clarity)
- 15. Seven monkeys ate 13 peaches, three for each big monkey and one for each little monkey. How many big monkeys do you have?
- 16. Seven monkeys ate peaches and 13 peaches in total. In order to know how many big monkeys there are, each big monkey ate three peaches and each little monkey ate two peaches?
- 17. Use 2,6,7,8,9,10, +, -, ×, △, (,), =, to form an expression. Use these numbers and operation symbols to form an expression Use these numbers and operation symbols to form a formula, each can only be used once
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- 19. What mathematical problems can be solved with 45 △ in the third grade of primary school
- 20. The circular equation of circle x2 + Y2 + 4x-4y + 4 = 0 with respect to the symmetry of line L: X-Y + 2 = 0 is