As for the math question, even one is fine, urgently, and it will be handed in tomorrow, thank you

1) A cylinder, its height increases by 3 centimeters, and the side area has been increased by square centimeters, and the bottom area of this cylinder is (square centimeters).

radius in centimeters. Base area square centimeters.

2) A cylinder with a height of 5 cm, sawn into two pieces along the diameter of the bottom surface, its surface area increases by 40 square centimeters, and the volume of this cylinder is (cubic centimeters).

Radius 40 2 5 2 = 2 cm.

Volume cubic centimeters.

3) A cylindrical bucket with a bottom circumference of centimeters and a volume of cubic centimeters, filled with four-fifths of a bucket of water, how many centimeters of water is the depth of the water? (columnar).

radius in centimeters. 40 cm. 4) (Note: This cylinder is cut from top to bottom, with a bottom diameter of 8 cm and a height of 10 cm) How many cubic centimeters of wood should be used to make such a block? (columnar).

Cubic centimetre. 5) If you paint the surface of the block, how many square centimeters is the area of the painted part?

Cm.

1) Bottom circumference:,Diameter:,Radius:1,Area:

2) Bottom diameter: (40 2) 5=4, radius: 2, volume: 2*2*

3) Bottom diameter: , radius: 8, area: 8*8*, height: , so water depth: 4

A rectangle is 25 long and 20 wide, if the length increases by 6 and the width increases by 4, find the area of the rectangle that increases. Hold and sell.

Analysis: This is a rectangular area problem, not very difficult, but it is easy to make mistakes, it is easy to calculate directly from the habit of 6 4 = 25, and the result is used as the increased area of the rectangle, in fact, this practice is wrong, as shown in the following drawback diagram, the actual increase in the area of the rectangle includes three parts - and 4 6 = 25 is only the actual increase in the area of , and it is also the area increased by Duan Bu Tea, this wrong practice misses the part. Answer:

That's the actual increase in area.

This question can also be calculated like this:

It can be seen that the results of the two calculations are consistent, which also shows that 244 is the real area of the increase.

<> from the figure, it can be seen that after the width and length increase at the same time, the overall increase in the area of the figure should be divided into three parts. The first part is an area with a length of 25 and a width of 4, the second part is an area with a length of 6 and a width of 4, and the third part is an area with a length of 6 and a width of 20.

And your 4 to 6, is only part of the increase in area.

The intersection of the length and width is 6x4 after the length and width are extended

The two triangles are congruent right triangles, and we align their corresponding sides to create the four convex quadrilaterals below.

Obviously, two right triangles are congruent.

To make a convex quadrilateral, you can only put equal sides together. Glued together with three equal edges, three different quadrilaterals can be obtained.

For example, the short right-angled edges are adhered to obtain a parallelogram with a long right-angled edge and an hypotenuse side of the side length.

The long right-angled edges are adhered to obtain a parallelogram with a short right-angled edge and an hypotenuse with an edge length.

The hypotenuse is adhered to obtain a long right-angled side and a short right-angled edge as a rectangle of side length.

Let x parts, profit = 20 * x * (, we can see that the profit increases with the increase of x, so when x = 400, the maximum profit is 825

Of course, 400 ah, you want to have 30 days in a month, and 20 of them can sell 400, and if you can't sell it, you will lose! In that case, only by entering 400 can you guarantee the maximum profit! That's a piece of. Pretty good!

Solution: If you buy x(250 x 400,x n) copies from the newspaper every day, you can sell a total of 20x+10(x+250) copies per month, and each copy can get a profit yuan, and return 10 (x-250) shares to the company, and each share loses yuan, establish a monthly net profit function f(x), and then find the maximum value of f(x) to get the maximum profit of a month.

If the total monthly profit of buying x newspapers from the newspaper is y yuan, then according to the title, y=,x [250,400].

The function y increases monotonically on [250,400], when x=400, y(max)=825 (yuan), that is, when the stall owner buys 400 copies from the newspaper every day, the monthly profit is the largest, and the maximum profit is 825 yuan.

The answers in the first few are correct, but the answers are incorrect.

Sell less than 250 copies a day, there is no return to the cooperative, you can make a profit of 25 yuan per day, and a profit of 750 yuan a month.

In the case of more than 250 copies, the difference between the profit of 20 days and the loss of the newspaper returned in 10 days should be considered. If you buy one more newspaper every day, you can earn 2 yuan in the 20 days of profit, and you have to post yuan for the 10 days you lose, so that you can still make a profit from these 30 newspapers in a month.

Therefore, after more than 250 copies a day, each additional copy can be more profitable, of course, the more you enter, the more profit.

Considering the daily sales volume, the maximum amount of profit that can be sold in 20 days should be as much as it should be.

Solution: Suppose you buy x copies per day, the monthly profit is y yuan, x 400y = 400*

2400+750+(30x-10500)*=3150+

When x=400, y has the maximum value, which is:

y=Yuan Answer: Buying 400 copies a day can make the maximum monthly profit, and you can earn up to 825 yuan a month.

The distance between a and b is (80 + 70) 2 = 300 (km).

Answer: Only the yards A and B are 300 kilometers apart.

Set: A and B meet after x hours.

80x-70x=10

10x=10

x = 1 so ab is far apart: 80 * 1 + 70 * 1-10 = 140 (km) A and B are 140 km apart.

(1) Obviously, every piece sold earns 50x (1-10%)-30=15 yuan, so why is there a loss? Because there is a monthly expense of 4500 yuan, so the net profit of selling at a loss must be equal to 4500, so the column formula is 4500 (50x90%-30), (it can be understood in this way: I want to get a total profit of 4500 yuan to remove the profit of 15 yuan per piece is the number of pieces to be sold).

2) To ensure that the income of the two sales methods is the same, it is obvious that the income of method 1 is more than 4500The available formula 4500 (50 90%-30-40 90%-30) can be understood as the income of method 1 is more than method 2 for every piece sold (15-6=9 yuan), then the profit is guaranteed to be the same, and the 4500 yuan of the income of method 1 is allocated to each piece, and the number of pieces can be obtained.

Solution: (1) If you need to sell x pieces to not lose money, according to the topic:

50x（1-10%）=4500

x=100, so you need to sell 100 pieces to not lose money.

2) Set the two methods to sell x pieces per month when the profit is the same, according to the topic:

50x(1-10%)-4500=40x(1-10%) x=500, when selling 500 pieces, the profit is the same with both methods.

The area of red silk is square meters = 2250 square decimeters, and the area of small red flags is (1 2) 5 5 = square minutes to change the wheel kemi, then: [2250] [face nuclear call.

The distance between the two cities is x km, and the speed of the bus is y km h. The meeting point should be to the right of the midpoint (near City B) because it is an express train from A to B. then there is (x 2 30) 75 (x 2 30)y