Make up a practical problem according to the requirement and answer your practical problem The writing requirements are as follows: 1. To write an applied problem of downstream and downstream water, so that the equation listed according to the meaning of the problem is 9 (x + 2) = 11 (X-2) 2. The structure of the applied problem is complete, the meaning of the problem is clear, and it is in line with the reality

It is known that the speed of the current is 2km / h. It takes 9 hours for a ship to go from a to B downstream and 11 hours for a ship to go from B to a upstream

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1. For any natural number n, we can prove that (n power of 3, n power of 4) = (3,4). The proof is as follows: let (n power of 3, n power of 4) = x, then NX power of 3 = n power of 4, i.e. (n power of X power of 3), so x power of 3 = 4, i.e. (3,4) = X, Thus (n-th power of 3, n-th power of 4) = (3,4). (1) according to the above provisions, (3,27) = (5,1) = (2) explain the reason why equation (3,4) + (3,5) = (3,20) holds
2. There are strict regulations on the quality of football used in formal football match, and the standard quality is 400g. The following are the quality test results of five football (use positive numbers to record the grams that exceed the specified quality, use negative numbers to record the grams that are less than the specified quality): - 25, + 10, - 20, + 30, + 15. (1) write down the quality of each football; (2) please point out which football has better quality, and use the absolute value We can judge by our knowledge
3. Seventh grade math problems, online speed~~~ As shown in the figure, the triangle ABC is an equilateral triangle, and the point D is the midpoint on the side of BC, which is the degree of ∠ B, ∠ DAC A triangle is isosceles with a vertical bisector in the middle It is known that in triangle ABC, ab = AC, ad bisects ∠ BAC, intersects BC with D, the circumference of triangle ABC is 36, and the circumference of triangle ADC is 30 cm
4. Mathematics problems of grade seven Xiaojie's family bought a new table of 1 or 2 meters. Grandma put two pieces of 1 meter long square cloth together to form a large square cloth. Can you express the side length of the cloth in radical form? Can this cloth cover the table
5. How many seventh grade math problems to solve! Urgent! Is the absolute value of rational numbers If | a | = | B |, then:_____ Or_____ If a + B = 0, then: If | x | = a (a > 0), then x has___ Values, x =______ They are______ Count Simplify 1. a＞1,| a - 1 | 2. a＜1, | a - 1 | 3. x＜2 | x - 2 | 4. x＜ - 3 | x + 3 | 5. -1＜x＜2 6.-1＜x＜2,|x+1|-|x-2| Given | 2 A + 1 | + | B - 2 | + | 3 - C | = 0, find ABC =? Given that | 3 x + 4 | and | 2 x - 1 | are opposite numbers, find x + y =? 5 A + 6 and 2 - A are opposite numbers, so 2A + 3B =?
6. 1、（）-3a²+5a-7=-2a²+2a+1 2. If a = x & sup3; - 5x & sup2; - 11x + 6, then A-B = () 3. If the value of the polynomial 3x & sup2; - 2 (5 + y-2x & sup2;) + MX & sup2; has nothing to do with the value of X, then M is equal to X
7. The area of the rectangle is 6m square + 60m + 150 (M is greater than 0). The ratio of length to width is 3:2. Find the perimeter of the rectangle. This is an application problem
8. Mathematics problems and answers on page 180 of Grade 7
9. The polynomial x ^ 2 + PX + 12 can be decomposed into the product of two first-order factors. The value of integral P is () write two
10. There is a column of numbers: A1, A2, A3 If A1 = 2, then a2007 is () A. 2007B. 2C. 12D. -1
11. Seventh grade math problems and answers Thank you
12. 1. If A2 + ab-2b2 = 0 and B ≠ 0, find the value of (2a-b) / (2a + b) 2. A + B = 1, find the value of A3 + B3 + 3AB
13. In order to promote the sale of a brand of air conditioner, a store decided to purchase the air conditioner on May Day in 2007. It can pay in two installments. When purchasing, it pays a sum of money in advance, and the rest and its interest (annual interest rate of 5.6%) will be paid before may day in 2008. The price of the air conditioner is 8224 yuan per unit. If the two payments are the same, how much yuan should be paid each time
14. If one digit and two digits are allowed (do not change the order of the given numbers, and do not add + or - in front of some numbers), can we still get 10 if we regard two consecutive numbers as two digits? Please write two or more formulas and give the numbers as 2, 3, 4, 5, 6, 7, 8, 9
15. The following statement is wrong () A. The sign of the result of multiplication of two rational numbers and division of the two rational numbers B. When two rational numbers are divided, the sign of quotient is determined first, and then the absolute value of quotient is calculated C. If one of the two numbers is equal to 0, then their product and quotient are equal to 0 D. If two negative numbers are divided, the quotient must be greater than 0 Please explain the reason! Additional points will be given if the answer is complete Sorry, option a is short of two words, it should be (the symbol of the result is the same)
16. A = 25, B = - 3, try to determine the number of a to the power of 2008 + B to the power of 2008 Practical questions: It is known that the distance between the two places is 213 km. Xiao Wang and Xiao Zhang start from the two places and travel in opposite directions. Xiao Zhang's speed is more than twice that of Xiao Wang's speed by 0.5 km / h. suppose Xiao Wang's speed is v km / h. After 6 hours, how many km are Xiao Wang and Xiao Zhang apart? An engineering team loaded cement poles from the warehouse and transported them to the side of the road which is just 1000 meters away from the warehouse. It is required to plant one pole 50 meters ahead along the side of the road. It is known that the engineering vehicle can transport up to 4 poles, and it is required to complete the task of transporting 21 poles and return to the warehouse?
17. In a hurry Given x ^ 2Y ^ 2-10xy + x ^ 2 + y ^ 2 + 16 = 0, find the value of x ^ 2 + y ^ 2
18. 1 mm is equal to? Micron; 1 micron is equal to?;
19. Complete square formula (2) Note: the number after brackets is the power (2X+Y-3)2 (A+3B-2)(A-3B+2) (X+Y+1)(1-X-Y) [X+(Y+1)][X-(Y+1)] (3X+Y-4)(3X+Y+4)-(3X+Y+4)(3X-Y-4)
20. In the plane rectangular coordinate system xoy, point a is a point on the bisector of the first quadrant angle, the distance from point a to the x-axis is 2, a moving point on the positive half axis of the Y-axis of point B, the vertical line of line AB passing through point a intersects the positive half axis of X-axis at point C (1) Finding the coordinates of point a (2) If the coordinates of point B (0,1), find the length of line BC