First, the correct choice (this big topic *** 10 small topic; 3 points for each small question, ***30 points)

The reciprocal of 1 -3 is ()

A.- the third century BC.

2. The following two algebraic expressions in each group belong to the same category ().

A, B, C, D,

3. As shown in the figure, which two geometries are the gyro made of? ( )

A. cuboids and cones B. rectangles and triangles C. circles and triangles D. cylinders and cones

4. Number, the position on the number axis is as shown in the figure, which is ()

A. positive numbers B. zero C. negative numbers D. are all possible

5. Two rational numbers are multiplied by the opposite number, and the product is ().

A. positive number B. negative number C. zero D. negative number or zero

6. Cut off a corner of the rectangle to get a graphic that must not be ().

A. pentagonal trapezoid rectangular triangle

7 Among the following algebraic expressions, the one that meets the writing requirements is ().

A. 6th century BC

8. Remove the brackets: -(-A+B- 1) The correct result is ()

A.-a+b- 1 b . a+b+ 1 c . a-b+ 1d .-a+b+ 1

9. Each term of the polynomial 2x2-3x-5 is ().

A.2x2，3x，5 B.2，-3，-5 C.2x2，-3x，-5 D.2x2 -3x-5

10. A rope is bent into the shape shown in Figure 3- 1. As shown in Figure 3-2, when the rope is cut along the dotted line A with scissors, the rope is cut into five sections. As shown in Figure 3-3, when the rope is cut again along the dotted line b(b∑a) with scissors, the rope is cut into 9 sections. If you cut the rope between dotted lines A and B (n 2) times with scissors (the direction of scissors is parallel to A), and cut it n times with scissors, the number of knots of the rope is ().

a . 4n+ 1 b . 4n+2 c . 4n+3d . 4n+5

Fill in the blanks accurately (3 points for each small question, * * * 24 points)

1 1. If the absolute value of a number is 3, then this number is.

12. The tomatoes in the market are a yuan per kilogram, and the cabbage is b yuan per kilogram. The school canteen needs 30 kilograms of tomatoes and 50 kilograms of cabbage.

_ _ _ _ _ _ _ _ _ Yuan.

13. According to the operation steps shown in the figure below, if the input value of x is -3, the output value is.

.

14. Observe each equation:12+1=1× 2,22+2 = 2× 3,32+3 = 3× 4, …, please use the integer n (n ≥ 65438+.

15 coefficient. -Yes.

16. "*" is the specified algorithm:, then the value of is.

17. If the water level of the reservoir is 3 meters higher than the standard water level, it will be recorded as +3 meters, and if it is 2 meters lower than the standard water level, it will be recorded as _ _ _ _ _ _ _ _ _ _ _.

The value of 18 is

Iii. Answering questions (***66 points)

16. (The score of this question is 16)

( 1)–2÷(- )×(-4.5) (2)

(3) (4)

17. (8 points for this question) Simplify before evaluating.

, in which

18. (9 points in this question) Draw three views of this geometry.

19. (7 points for this question) 3. The schematic diagram of a mine is shown in Figure 2- 16: Based on the ground, the height of point A is+4m, and the heights of point B and point C are–15m and–30m respectively. How much higher is point A than point B? What about point C?

20. (6 points for this question) Arrange the consecutive even numbers 2, 4, 6 and 8 ... in the table below, and cross out five numbers (as shown in the figure).

2 4 6 8 10 12

14 16 18 20 22 24

26 28 30 32 34 36

38 40 42 44 46 48

……

(1) What is the relationship between the sum of five numbers in the cross box and the number 20 in the middle of the box?

(2) If the cross box moves up, down, left and right, but the five numbers in the sequence must be framed, if the middle number is a, the algebraic expression of a is used to represent the sum of the five numbers enclosed in the cross box;

2 1.( 10 point) Please pay attention to the following points:

- 1× 12 = - 1+ 12

- 12 × 13 = - 12 + 13

- 13 × 14 = - 13 + 14

…

(1) What laws can be explored? (in words or expressions)

⑵ Try to use the law you found to calculate.

(- 1× 12 )+(- 12 × 13 )+(- 13 × 14 )+…+(- 12007 × 12008 )+(- 12008 × 12009 ):

22. (This question 10) The school needs to print X copies of materials in the printing factory. A printing factory proposed to charge 0.2 yuan printing fee and 500 yuan plate-making fee for each material; Printing factory B proposed that 0.4 yuan printing fee should be charged for each material, and plate-making fee should not be charged.

(1) What are the charges of the two printing houses? (represented by an algebraic expression containing x)

The school has to print 2400 copies of materials. If other factors are not considered, which printing house is more cost-effective? Try to explain why.