1, A and B are s kilometers apart, and the time t (hour) taken by someone to complete the trip and his speed v (kilometer/hour) satisfy vt = s. During this change, the following judgment is wrong ().
A and s are variables b, t is variable c, v is variable d, and s is constant.
2. Variables X and Y have the following relationships: ① X-Y = 5; ②y2 = 2x； ③:y = | x |； ④y=, where y is x and the function is ()
a、①②③ B、①②③④ C、①③ D、①③④
3. Xiaojun 50 yuan bought a notebook with a unit price of 8 yuan, so the relationship between his remaining money Q (yuan) and the number X he bought this notebook is ().
a、Q=8x B、Q=8x﹣50 C、Q=50﹣8x D、Q=8x+50
Second, fill in the blanks
4. In 3x-y = 7, the variable is (), the constant is (), and it is written in the form of X as ().
5. Function y = | x-b |. When x= 1 or 3, the corresponding two function values are equal, so the value of real number b is ().
6. The following is the word "Shang" composed of chess pieces: continue to put it down according to the rules in the figure, and the relationship between the number of chess pieces required for the nth word "Shang" and N is ().
Third, answer questions.
7. Write the relationship in the following questions, and point out the variables and constants.
(1) The relationship between an acute angle A and another acute angle β in a right triangle;
(2) The water tank filled with 30 tons of water flows out 0.5 tons of water per hour, and the trial operation time t (hour) represents the remaining water y (ton) in the water tank.
8. The circumference of an isosceles triangle is 10cm, the base length BC is ycm, and the waist length AB is xcm.
(1) Write the functional relationship between y and x;
(2) Find the value range of x;
(3) Find the value range of y,
9. A car has 50 liters of gasoline in its fuel tank. If you don't refuel, the fuel quantity y(L) in the fuel tank will decrease with the increase of mileage x(km), and the average fuel consumption is 0, 1L/km.
(1) Write the functional relationship between y and x.
(2) point out the range of independent variable x.
(3) How much gasoline is left in the fuel tank when the car is driving for 200km?
10. With the support of the community, Sister-in-law Yang founded the newspaper retail point Runyang, and provided the following information for an evening newspaper:
(1) Buy each 0, 50 yuan, and sell each 0 1 yuan;
② Within one month (30 days), 200 copies can be sold every day for 20 days, and only 120 copies can be sold every day for the remaining 10 days;
(3) Within one month, newspapers bought from newspapers every day must have the same number of copies, and newspapers that can't be sold that day will be returned to newspapers at 0.20 yuan per copy.
(1) When the daily circulation of this evening paper in one month is 100 and 150 respectively, what is the monthly profit?
(2) Which of the above quantities are changing? What are independent variables and functions?
(3) If you buy X copies of this evening paper from the newspaper every day (120≤x≤200) and the monthly profit is Y yuan, please write down the relationship between Y and X to determine the highest monthly profit.