It is known that a salt factory exposed 3000 tons of salt, and the factory decided to transport all the salt away. (1) What is the functional relationship between the transportation time t (day) and the transportation speed v (ton/day)? (2) If the salt factory has 80 workers and can transport up to 500 tons of salt every day, it is estimated that it can be shipped out in a few days at the earliest. (3) If the workers in this salt factory work for three days, the weather forecast predicts that there may be heavy rain in the next few days, so the salt factory decides to transport all the remaining salt within two days. How many people need to be transferred from other salt factories? Thinking and analysis, we know that this is an engineering problem, and the key is to be familiar with the relationship between quantity and quantity in this kind of problem. (1) the total amount of salt = the time required to transport all the salt × the salt transport speed, and the functional relationship between t and v can be obtained. (2) It transports 500 tons of salt every day, that is, v=500. If v=500 is substituted into the functional relationship in (1), the corresponding t can be obtained; (3) Assuming that N people are transferred from other salt plants, N can be obtained by equation according to the residual salt = salt transported by 80 workers+salt transported by N workers. Solution: (1) T = (2) When v=500, T = = 6, that is, the salt can be shipped out within 6 days at the earliest. Multiple-choice questions: Y decreases with the increase of X, then its images are distributed in A. The first and second quadrants B. The first and third quadrants C. The second and third quadrants D. The second and fourth quadrants () 2. Given that the image of the inverse proportional function Y = is in the second and fourth quadrants, the range of a is a.a ≤ 2b.a ≥ 2c.a < 2d. Then its image must also pass through A. (-a, -b) B. A.(-a, -b) C. (-a, b) d. (0,0) () 4. In the same rectangular coordinate plane, if the straight line y=k 1x does not intersect the hyperbola, then the relationship between k 1 and k2 must be a.k1k2 = 0b.k1k2 >1c.k/kloc-0. In the same rectangular coordinate system, the approximate images of functions y= k (x- 1) and y= are () 6. It is known that there are two points A(x 1, y 1) and B(x2, y2), x 1 < x2 0) on the image of inverse proportional function. Try to explain y 1 and y2 by calculating or using the properties of inverse proportion. (10 point)10000.0000000006 (2) If the image of the linear function y2=kx+b intersects the Y axis at point C, find the area of △AOB (O is the coordinate origin); (3) the range of x when finding y 1 > y2. (6+4+4= 14 points) 17. In recent years, coal mine safety accidents have occurred frequently in China, among which gas is the most harmful, and its main component is Co. In the investigation of a mine accident, it was found that the concentration of CO in the air in the well after the explosion decreased inversely from zero. As shown in figure 1 1, answer the following questions according to the relevant information in the question: (1) Find the functional relationship between the concentration of CO in the air before and after the explosion and the time x, and write the corresponding independent variable range; (2) When the CO concentration in the air reaches 34 mg/L, the miners 3 km underground will receive an automatic alarm signal. At this time, how many km/h must they evacuate to explode? (3) Only when the concentration of CO in the air drops to 4 mg/L or below can the miners return to the mine to save themselves, and how many hours can the miners go down after the explosion? (6+4+4= 14 points) Reference answer: 1. Multiple choice questions: b; c； a； d； b； b； B 2。 Fill in the blanks: 8. 9. (The answer is not unique); 10.； 1 1.； 12.； 13. III. Solution: 14. (1), in 15. (1) p (1, -3), y =-2x- 1 (2) Therefore, knowing the points (0,4) and (7,46) in the image, the functional relationship between y and x can be set to ∴ ∴. At this time, the value range of the independent variable is 0≤ ≤7. (If you don't take =0, you can put =7 in the second function. ) because the concentration decreases in reverse after the explosion, you can set the functions of y and x, and the range of independent variables is > 7. (2) When =34, then 6 +4=34, =5. ∴ The longest evacuation time is 7-5=2 (hours). ∴ The minimum evacuation speed is 3 ÷ 2 = 1.5 (km/.

(3) Assuming that N people need to be transferred from other salt plants, according to the meaning of the question, it is concluded that n=40, that is, 40 people need to be transferred from other salt plants. To sum up this problem, the relationship is: the total amount of salt = the time required to transport all the salt × the speed of salt transport. Of course, the relationship between the three can be transformed into each other. Usually, as long as two of them are known, the third quantity can be found or expressed. Question (2) is actually an evaluation question, just substitute it in (1); Problem (3) is solved by means of an equation. The third section, wrong question analysis 1. In the inverse proportional function, remember that k≠0 is 1. If the function is an inverse proportional function, then m= Wrong solution: Because it is an inverse proportional function, |m|= 1, so m = 1. K is a constant) is called an inverse proportional function. The definition emphasizes the condition that the coefficient k≠0 and k is constant. The wrong solution ignores the condition of k≠0. In this question, m- 1 is equivalent to k in the definition, and there should be m- 1≠0, so M ≠ 650. So, m ≠ 1. Therefore, m=- 1. Reflection: To solve the problem of letter selection in inverse proportional function, we must pay attention to the restriction condition of k≠0, otherwise it is easy to make mistakes. Second, pay attention to the range of independent variables. Example 2: The area of a rectangle is 10, so the length y of a set of adjacent sides of this rectangle is equal to.