A cone-shaped beach has a bottom diameter of 6 meters and a height of 0.9 meters. If each cubic meter of sand weighs 0.4 tons, how many tons does this pile of sand weigh? (the number is reserved to 10)

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• 1. On the mathematical problem of equal ratio In the equal ratio sequence {an}, A1 = - 3, A5 = - 12, then the value of A6 is equal to?
• 2. I'd like to ask some math questions for high school students, 1. The gravitational force F between a satellite and the earth is given by the formula F = GMM / R, where m is the mass of the earth and G is a constant 2. During the summer vacation, a travel agency launched the following method of group formation: for groups with 100 people, each person charges 1000 yuan. If the number of groups exceeds 100 people, the average charge per person will be reduced by 5 yuan for each more than one person, but the number of groups can not exceed 180 people. How to form a group, but the travel agency charges the most? 3. The area of a certain type of printing paper is 623.7cm square, and the margins of the upper and lower pages are required to be 2.54cm respectively, and the margins of the left and right pages are required to be 3.17cm respectively. If vertical printing is required, what is the length and width respectively to make the maximum printing area (accurate to 0.01cm)
• 3. Try to write a polynomial satisfying the following conditions at the same time: (1) Contains only the letter X (2) There is no constant term (3) The number of times is two (4) The coefficients of all the monomials are one
• 4. A kind of bottled beverage produced by a beverage company is printed with "600 ± 30ml" on the outer package. What is the meaning of "± 30ml"? Expression
• 5. Given that the square + Ma + 9 of polynomial A is a complete square expansion, then the value of M is ()
• 6. Q1: given (a + b) & sup2; = 9, ab = - 3 / 2, then a & sup2; + B & sup2; equals () Q2: given (a + b) & sup2; = m, (a-b) & sup2; = n, then AB equals () Q3: if a + B = 3, then the value of 2A + 4AB + 2B & sup2; - 6 is () Q4：（ _____ ） ·（-2mn）=4mn-2m²n². Q5: if the polynomial 9m & sup2; + 1 plus a monomial is a complete square with m, please write a monomial that meets the requirements:_______ . Q6: if a + B = - 3, ab = 2, then a & sup2; + B & sup2=_______ ,（a-b）²=______ .
• 7. 1. There are 9 playing cards, and their points are 1 23 4 5 6 7 8 9. It is known that the average number of 5 playing cards on the left is 6, and the number of points of 5 playing cards on the right is 4. What is the card in the middle? 2. The bottom radius and height of the two containers are 5cm and 15cm respectively. First put two pieces of ice into the cylinder, and then pour all the juice in the cone into the cylinder. This is the height of the liquid level in the cylinder, which is 7cm (the ice is completely submerged). Calculate the area of the original two pieces of ice 3. Father and son start from the starting point of 100m runway at the same time and walk to the terminal at a constant speed. When father walks 40m, son walks 30m. According to this calculation, when father reaches the terminal, how many meters is the son away from the terminal? If father returns immediately after reaching the terminal, how many meters will he meet his son?
• 8. 1 if 2x + 5y-3 = 0, find the x power of 4 times the Y power of 32 2 known: a + 2B = 0 prove: the third power of a + 2Ab (a + b) + the third power of 4B = 0 Try to judge the last digit of the power 2009 of 2010 + the power 2010 of 2009
• 9. Solving math problems with equations in Grade Seven Entering the flood season, the students of class 1, Grade 7 went to the reservoir to investigate the flood situation There are 10 flood sluices in total. Now the water level of the reservoir exceeds the safety line, and the river water in the upper reaches still flows by one Constant speed into the reservoir, students after a day of observation and measurement, do the following Record: one sluice gate was opened in the morning, and the water level continued to rise within 2 hours 66km. After opening two sluice gates in the afternoon, the water level dropped by 0.1M in 4 hours. At present, the water level of the sluice gate is lower than that of the sluice gate The water level is still 1.2m above the safety line (1) If five sluice gates are opened, it will take several hours for the water level to drop to the safety line ? (2) If the flood control headquarters requires the water level to drop to the safety line within 6 hours, it should call again How many floodgates are open? Please give me the process thank you The unit of 0.66 is meter
• 10. Some of the same rooms need wall painting. Three first-class technicians go to paint eight rooms a day. As a result, there are 50 square meters of future wall painting and painting. In the same time, five second-class technicians paint another 40 square meters of wall besides 10 rooms. Each first-class technician paints more than 10 square meters of wall in one day than the second-class technician, so the wall area of each room needs painting There are a group of pigeons and some pigeon cages. If 6 pigeons live in each pigeon cage, the remaining 3 pigeons have no pigeon cages to live in. If another 5 pigeons fly together with the original pigeons, each pigeon cage just lives in 8 pigeons. How many pigeons and pigeon cages are there?
• 11. A farm originally planned to sow 2000 mu of wheat in several days, but in actual sowing, the sown area per day was 30 mu more than the original plan, which not only completed the task within the specified time, but also sowed 240 mu more wheat. How many mu of wheat per day was the original plan? How many days was the original plan? Lie equation
• 12. 2（3x-1）²-32=0 27（1-4x）³=125 Find the value of X
• 13. 1. Both Party A and Party B set out from a to B at the same time at a speed of 15km / h. When Party A finds that the important goods are placed in a, they immediately return to get the goods and catch up with Party B. if the speed of returning and catching up with Party B is 1.2 times of the original speed, Party B's speed remains unchanged, and both of them reach B at the same time, the distance between two places of AB is calculated 2. When 100 g of 25% sulfuric acid solution is prepared with 50% and 10% sulfuric acid solution, how many g of 50% sulfuric acid solution is prepared?
• 14. Seventh grade math problems (to process!) 1. Given A-2 + B-3 = 0, find the value of B to the second power of 3AB + 2Ab (the second power of B) - the second power of 4A (the second power of a) 2. If a + B and A-B are opposite numbers, simplify the power of 2008 of a + the power of 2008 of B + the power of 2008 of a - the power of 2008 of B 3. How thick is a piece of paper with a thickness of 0.1 mm if it is folded 20 times? How many floors is it? (to be precise, suppose a floor is three meters high) 4. Known: M = m + m to the power of 2 + m to the power of 3 +... + m to the power of 200 (I) when m = 1, find m; (II) when m = - 1, find m; (III) when M-0, find M 5. If the n-th power of (- 4) is greater than 0 and the m-th power of (- 4) is less than 0, compare the m-th power of (- 1) + (- 1) with the n-th power of 3 + (- 3) 6. A / A + B / B + C / C = - 1, find the value of AB / AB + BC / BC + ABC / ABC To write the process! Well written, give points!
• 15. 1. As shown in the figure, in a quadrilateral, ab ‖ CD, points E and F are on the sides AD and BC respectively, connecting AC and intersecting EF with G, angle 1 = angle BAC 【1】 Verification of EF ‖ CD 【2】 If ∠ CAF = 15 °, 2 = 45 ° and 3 = 20 °, calculate the degree of ∠ B and ACD 2. As shown in the figure, it is known that AD and AE are respectively the middle line and high line of △ ABC, and ab = 5cm, AC = 3cm. Find the perimeter difference between [1] △ abd and △ ACD 【2】 If BF is the bisector of △ abd, what is the area of s △ BFD? 3. As shown in the figure, it is known that in △ ABC, the bisector of ad bisection ∠ BAC intersects BC at D, ∠ ABC, the bisector of ∠ ACB intersects ad at O, and goes through o to make OE ⊥ BC at E. try to guess the relationship between ∠ BOD and ∠ EOC, and prove your conclusion worry
• 16. As shown in the figure, in the quadrilateral ABCD, e and F are the intersection points of two groups of opposite extension lines respectively. Eg and FG divide ∠ BEC and ∠ DFC equally. If ∠ ADC = 60 ° and ∠ ABC = 80 °, then the size of ∠ EGF is () A. 140°B. 130°C. 120°D. 110°
• 17. As shown in the figure, the shadow part is a square piece of paper with a side length of 4cm. Cut a small square piece of paper with a side length of 2.5cm in the center of it. Please try to make a rectangle with the simplest method to make its area equal to the area of the shadow part in the figure
• 18. If x = 1, y = 6 and x = - 3, y = - 4 are solutions of the equation AX + by + 7 = 0, try to judge whether x = 3, y = 11 are solutions of the equation AX + by + 7 = 0
• 19. Given that a and B are the lengths of two sides of an isosceles triangle, a and B satisfy B 2 + a − 1 + 4 = 4b, the perimeter of the triangle can be obtained
• 20. There is a column of numbers: A1, A2, A3 If A1 = 2, then a2007 is () A. 2007B. 2C. 12D. -1