2、B

3. A.

4. A.

5、D

6. A.

7、(3,0)(0,9)

8、y=0.5x-0.5

9、3

10、- 1

1 1、x？ five

12、>

13, (1) Substitute x=2 and y=-3 into y=kx-4 to get -3=2k-4.

? K= 1/2, so the analytical formula of the linear function is y= 1/2x-4.

(2) Shift the image of y= 1/2x-4 upward by 6 unit lengths to obtain y= 1/2x+2. When y=0, x=-4, so the coordinate authority of the intersection of the translation image and the X axis is (-4,0).

14 、( 1)n 2n- 1

(2)y=3n- 1(n is a positive integer)

15 、( 1)y=-2x+8

(2)3

y=2/3x

16 、( 1)y = 600 x+ 1000( 150-x)，y=-400x+ 150 000

(2) According to the meaning of the question, 150-x? 2x，x？ 50.∫-400 < 0, from the nature of linear function, when x =50, y has a minimum value,? 150-50= 100. Therefore, a job can recruit 50 people and a job can recruit 100 people, and the monthly salary can be at least.

17 、( 1)y 12t(0？ t？ 1/2); y=-0.8t+6.4(t？ 1/2)

(2) if y? 4 o'clock, then 1/3? t？ 3, so it is effective at 7:20- 10:00 after taking the medicine at 7:00.

30 tons 18 and (1) oil need 10 minutes.

(2)Q 1=kt+b, because after passing through points (0,36) and (10,65), we can get: Q 1=2.9t+36(0? t？ 10)

(3) According to the image, the fuel consumption per minute of the conveyor is 0. 1t, so the fuel consumption of 10h is 10h? 60? 0. 1 = 60 (t) < 65 (t), so the oil is enough.

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