First, multiple choice questions

1, the arithmetic square root of a number is 9, and this number is ().

8 1 (B) 8 1 (C) 3 (D) 3

2. The following car logo, there are () is a central symmetry graphics, but not axisymmetric graphics.

2 (B)3 (C)4 (D)5

3. If the average of data 1, 2,2 and x is the same as the mode, then x is equal to ().

1 (B)2 (C)3 (D)4

4. Xiaoming rotates the following four cards 180 to get three cards, and the card that hasn't moved is ().

2 (B)4 (C)6 (D)8

5. Quadrilateral ABCD, only choose the combination of the following two conditions to make ABCD a parallelogram. A * * *, how many different combinations are there? ( )

AB‖CD BC‖AD AB=CD BC=AD

(A)2 groups (B)3 groups (C)4 groups (D)6 groups

6. the linear function y=kx+b satisfies (1) that y decreases with the increase of x (2) its image intersects the negative semi-axis of the y axis, and its function expression may be ().

(A)y = 2x+3(B)y = x-2(C)y =-x+4(D)y =-3x- 1

7, any triangle, any quadrilateral, any pentagon, any hexagon can be dense graphics is ().

(a) Any triangle, any quadrilateral; (b) any pentagon, any hexagon

(c) any triangle, any hexagon; (d) Any quadrangle, any hexagon

8. It is known that the Yangtze River is 836 km longer than the Yellow River, and the length of the Yellow River is 6 times longer than the Yangtze River, 1284 km. Let the lengths of the Yangtze River and the Yellow River be x km and y km respectively, then the following equation is correct ().

(A) x-y=836 (B) x-y=836

5x-6y = 1284 6y-5x = 1284

y-x= 836 (D) y-x= 836

6y-5x = 1284 5x-6y = 1284

Second, fill in the blanks:

The square roots of 9 and 4 are.

10，x