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The application problem of inequality in the second volume of seventh grade mathematics is difficult to solve
Company A has 12 agricultural vehicles and 6 agricultural vehicles in warehouse A and warehouse B respectively. Now it is necessary to transfer a county 10 and b county 8. It is known that the freight charges of 1 agricultural vehicles transported from warehouse A to counties A and B are 40 yuan and 80 yuan respectively. 1 The freight charges for transporting agricultural vehicles from warehouse B to counties A and B are 30 yuan and 50 yuan respectively. ?

(1) Assume that X agricultural vehicles in County A are shipped out from Warehouse B, and find the functional relationship between total freight Y and X;

(2) If the total freight is required not to exceed 900 yuan, how many transportation schemes are there?

(3) Find the transportation scheme with the lowest total freight. What's the lowest freight?

The cost per kilogram of chocolate candy produced by a food factory is 24 yuan, and its sales plan is as follows:

Scheme 1: If it is sold directly to the sales department of our factory in Wuhan, it costs 32 yuan per kilogram, but the sales department needs to pay relevant fees every month.

2,400 yuan;

Option 2: If sold directly to local supermarkets, the ex-factory price is 28 yuan per kilogram. If only one scheme can be used for sales every month, each scheme can sell all the products of the month every month, and the monthly sales volume of this factory is xkg.

(1) If you are the factory director, how should you choose the sales plan to make the factory get more profits in that month?

(2) After the factory director saw the report on the relationship between sales volume and profit in the first quarter sent by the accountant (the following table), he found that the sales volume filled in the table did not match the actual situation. Please find out the difference and calculate the actual total sales in the first quarter.

January February March

Sales volume (kg)? 550 ? 600 ? 1400

Profit (yuan)? 2000 ? 2400 ? 5600

The demand (10,000 pieces), supply y2 (10,000 pieces) and price X (yuan/piece) of a commodity in Taizhou area roughly meet the following functional relationships: y 1=-2x+90, y2=3x-40 (when the demand is 0, the supply stops). At that time, the price of goods was called stable price and the demand was called stable demand.

(1) Find the stable price and demand of commodities;

(2) When the price is in what range, the demand for goods is lower than the supply?

(3) When the demand is higher than the supply, the government often increases the supply price by providing price subsidies to the supplier, thus increasing the supply. If the steady demand increases by 30,000 pieces, how much subsidy should the government provide for each commodity to make the supply equal to the demand?

Read the following materials:

If two positive numbers a and b are a >;; 0, b>0, has the following inequality:?

If and only if a=b is equal, we call it the arithmetic mean of positive numbers A and B and the geometric mean of positive numbers A and B, so the above inequality can be expressed as: the arithmetic mean of two positive numbers is not less than (that is, greater than or equal to) their geometric mean. It is widely used in mathematics and is a powerful tool to solve the maximum problem. Here's an example:

Example: Given x>0, find the minimum value of the function.

Solution: If, then, if and only if, at instant x=2, the function has a minimum value, and the minimum value is 2.

Answer the following questions according to the above.

(1) known x>0, then when x = _ _ _ _ _ the function takes the minimum value, and the minimum value is _ _ _ _ _;

(2) Enclose a rectangular garden with an area of 100cm2 with a fence, and ask what the length and width of this rectangle are and what the shortest fence perimeter is; ?

③ When x>0 is known and the independent variable takes any value, the function takes the maximum value. What is the maximum value?

A bookstore is selling some extra-curricular books. The purchase price is 12 yuan/copy, and the price is 20 yuan/copy. In order to promote sales, the bookstore decided to reduce the price by 0. 10 yuan for each class that buys more than10 copies (for example, a class buys 20 such extracurricular books, and the price is reduced by 0. 10×.

(1) How many copies can a class buy at least, so as to get the lowest price? ?

(2) Write down (X >;) when buying x copies at one time; 10), the functional relationship between profit y (yuan) and purchase amount x (book); ?

(3) One day, Class 9 (1) of a school bought 46 books and Class 2, Grade 9 bought 50 books. The bookstore found that selling 50 books made less money than selling 46 books. In order to make more money by selling more books at a time, the lowest price should be 16 yuan/book, and other promotion conditions remain unchanged. How much should it be improved at least? Please provide a justification for the answer.