2. If 7a+9 | b | = 0, ab must be ().

(a) positive number (b) negative number (c) non-negative number (d) negative number

3. The 2003rd power of the reciprocal of the sum of A and B is equal to 1, and the 2005th power of the inverse sum of A and B is also equal to 1, then ()

2 (B)2 (C) 1 (D) 0

4. As shown in the figure, the bottom BC of the triangle ABC is 3 cm long and the side BC is 2 cm high.

Move the triangle upward in the high direction at a speed of 3 cm per second for 2 seconds. At this time,

The area swept by the triangle is () square centimeters.

(A)2 1(B) 19(C) 17(D) 15

Xiao Ming's mother bought 3 Jin of grapes and 2 Jin of apples in the market before the Spring Festival, and spent 8 yuan. After the Spring Festival, she went to the market to buy these two kinds of fruits. Because the price per kilogram of grapes rises by 50 cents, the price per kilogram of apples drops by 30 cents, and it takes 2 1 yuan to buy 7 kilograms of grapes and 5 kilograms of apples. When shopping after the Spring Festival, the price per kilogram (grapes and apples) is () respectively.

(A) (2.5，0.7) (B)(2， 1) (C)(2， 1.3) (D) (2.5， 1)

6. When x=- 1, the value of algebraic expression is 18. The algebraic expression 9b-6a+2= ().

(a) Articles 28 (B) to 28 (C) and 32 (D) to 32

7. The sum of n different positive integers is less than 50. The maximum possible value of n is ()

10 (B) 9 (C) 8 (D) 7

8. If it is known that the complementary angle of the sum of ∠A and ∠B is equal to the complementary angle of the difference between ∠A and ∠B, then ∠B= ().

75 (B)60 (C) 45 (D) 30

9. As shown in the figure, the six faces of the square are marked with the numbers 1, 2 and 3 respectively.

4,5,6。 The number displayed according to the three states in the figure, "?" table

The number displayed is ()

1 (B) 2 (C)4 (D) 6

10. If both A and B are rational numbers and A-2ab+2b+4a+8 = 0, then ab= ().

8th meeting in 2004

1 1. If the positive integer x, y satisfies 2004x= 15y, then the minimum value of x+y is _ _ _ _ _.

12. The sequence of 1, 1, 2, 3, 5, 8, 13, 2 1, 34, 55, … is: the first two numbers are 1, from.

13.3.2004 Write 6/3/2004 according to American custom and 3/6/2004 according to British custom, such as 6/3/2004. It is difficult to judge whether it is an American date or a British date, and it is also difficult to judge which day it is. This is called a confused date. While 4/ 18/2004 is obviously an American date, which can be accurately judged as April 20041813; 18/4/2004 is obviously an English date, which can be accurately determined as April 200418; 2/2/2004 Although we can't be sure whether it is an American date or a British date, we can always be sure that it is February 2, 2004. These are mixed dates. Then there are _ _ _ chaotic dates every month; There are _ _ _ mixed dates in 2004.

15. As shown in Figure 3, two ships, A and B, sailed from Port B to Port C and Port A respectively.

Port driving. It is known that the speed of ship A is twice that of ship B, and port A and port B are in phase.

It's 540 kilometers away. Ship a will arrive at port c in three hours, and then sail for a immediately.

Port, and finally arrive at port A at the same time with B ship, then the speed of B ship is _ _ _ _ km/h. 。

16. If n is a positive integer, and if the unit number

The number of digits of n is 6, that of n is 9, and that of n is _ _ _ _.

(English-Chinese small dictionary unit digits: single digits)

17. Enclose a rectangle with several line segments of length L. The greatest common divisor of the length and width of the rectangle is 7 and the least common multiple is 7× 20. Then at least _ _ _ _ _ line segments with the length of 1 are needed to enclose this rectangle with an area of _ _ _ _ _ _ _.

1 8. The sum of the solutions of the equations of x and y is equal to1,then the value of m is _ _ _ _ _.

19. Two typists, A and B, type 500 words per page and B type 600 words per page. It is known that if A writes 8 pages, B can write 7 pages. If A finishes typing 2 pages and B starts typing, then when A and B type the same number of words, B will type _ _ _ _ _.

20. Write 2004 as the product of several prime numbers. If a, b and c are three of these prime numbers, and a

Third, solve the problem (requirements: write out the calculation process. )

2 1. Observe the following equation.

2×2=4, 2+2=4

,

,

,

(1) Xiao Ming summed up the above categories and got a guess: "The product of two rational numbers is equal to the sum of these two rational numbers". Is Xiao Ming's guess correct? Why?

(2) Please observe the above structural features, sum up a guess and prove your guess.

23. Fill in 9 identical positive integers in the 3×3 grid table: 1, 2,

3, 4, 5, 6, 7, 8 and X, so that these three numbers are filled in each row and column.

Two sums are equal. Please determine the value of x and give a filling method.