Math problems, trouble everyone, math problems, trouble everyone...

1. The surface area is 6 2=3 square centimeters, because the surface area of the cylinder is composed of two bottom areas and a side area, and the side area of the cylinder can be obtained according to a rectangle, and then the base area is obtained according to the factory of the rectangle, that is, the perimeter of the bottom surface, and the surface area is obtained.

The volume is the base area multiplied by the height i.e. cubic centimeters.

96 2= (the length of the side area of the cylinder, which is also the circumference of the circle of the base area) Diameter) 7 2 = radius) the base area) cubic decimeters (the volume of the cylinder).

3. According to the formula 1 3sh=v, that is, 1 3*6*s= find s= (bottom area) and cubic centimeters of the volume of the cylinder of the same height as the bottom.

4. Get a (cone) volume of: 1 3 * cubic centimeters.

5 liters = 2500 ml 2500 50 = 50 bottles.

04h=1 3xh Because h is equal, x=square centimeter.

7. Because the cylinder and the cone are equal in height at the bottom, 1 3sh + 32 = sh gives sh = 48 (cylindrical volume) The cone volume is 1 3 * 48 = 16 cubic meters.

1 3 = 8 cubic centimeters.

1.Put the side of a cylinder is a rectangle, the length is centimeters, and the width is 8 centimeters, then the surface area of the cylinder is ( ) and the volume is ().

2.The side area of a cylinder is decimeter squared, the height is 2 decimeters, and its volume is () cubic decimeter.

3 The volume of a cone is cubic centimeters, the height is 6 centimeters, its base area is (), and the volume of a cylinder of equal height is ().

4.A right-angled triangle with two right-angled sides of 3 cm and 6 cm respectively, rotated around the axis of the long right-angled side, can give a () body, and its volume is ().

5.There are liters of potions, and if you put all these potions in a bottle with a capacity of 50 ml, you can fill the () bottle.

6.The volume and height of a cylinder and a cone are equal, and the base area of the cylinder is a square centimeter, then the first area of the cone is ().

7.A cylinder and a cone are equal in height, and their volume differs by 32 cubic meters, the volume of this cylinder is (), and the volume of the cone is ().

8.A cylinder with a volume of 24 cubic decimeters is cut into the largest cone, and the volume of the cone is () cubic centimeters.

Answer: 1. The surface area is 6 2=3 square centimeters, because the surface area of the cylinder is composed of two bottom areas and a side area, and the side area of the cylinder can be obtained according to a rectangle, and then the bottom area is obtained according to the rectangle, that is, the perimeter of the bottom surface.

The volume is the base area multiplied by the height i.e. cubic centimeters.

96 2= (the length of the side area of the cylinder, which is also the circumference of the circle of the base area) Diameter) 7 2 = radius) the base area) cubic decimeters (the volume of the cylinder).

3. According to the formula 1 3sh=v, that is, 1 3*6*s= find s= (bottom area) and cubic centimeters of the volume of the cylinder of the same height as the bottom.

4. Get a (cone) volume of: 1 3 * cubic centimeters.

5 liters = 2500 ml 2500 50 = 50 bottles.

04h=1 3xh Because h is equal, x=square centimeter.

7. Because the cylinder and the cone are equal in height at the bottom, 1 3sh + 32 = sh gives sh = 48 (cylindrical volume) The cone volume is 1 3 * 48 = 16 cubic meters.

1 3 = 8 cubic centimeters.

Solution: Let the number in the single digit be x and the number in the ten digit is 2x+3x+10(2x+3)-45=10x+2x+3x+20x+30-45=12x+3

21x-15=12x+3

21x-12x=15+3

9x=18x=22×2+3=7

A: The original two-digit number was 72

2. Solution: Set B is now x years old.

2(x-5)=x+15-5

2x-10=x+10

2x-x=10+10

x=20A: B is now 20 years old.

(1) Let the number of tens be x and the single digit is y, then x = 2y+3 and the following condition gives 10y+x+45=10x+y, and we get x=7 y=2

2) Let B be x years old now then.

15+（x-5)=2(x-5)

x=20

Let the original two-digit number be ab, which can be known according to the title.

1, a=2b+3, b can take 1,2,3, and then substitute these three numbers into the following equation 2, ab-ba=45

The solution is a=7 and b=2, that is, the original two-digit number is 72

Let x tens of digits and y single digits.

x=2y+3

10x+y-(10y+x)=45

Personal habits: Calculate that the child should solve it on his own.

9000 (1-94%) = 540 ......Less profitable money.

The original price of 20 units is considered as a unit of "1".

540 (1-85%) = 3600 yuan ......Unit "1" is the original price of 20 units.

3600 20 = 180 yuan ......The original pricing per unit.

180 (1+20%)=150 yuan ......The original purchase price of each unit.

9000 (180-150) = 300 units ......The number of fans in this batch.

The actual less profit: 9000 * (1-94%) = 540 The reason for the less profit is that 20 units are sold at a discount of 85% at the sales price, then the original total price:

The unit price is 3600 20=180

The purchase price is 180 (1+20%)=150

9000 (180-150) = 300 units ......

The total purchase price of all electric fans is 9000 yuan, and the estimated total selling price is 45000 + 9000 = 54000 yuan, and the loss of profit is 9000 * (yuan.

The estimated total sales price of the 20 electric fans with loss is 540 yuan (yuan, and the selling price of each electric fan is 3600 20 = 180 yuan, and the number of electric fans is 54000 180 = 300 yuan.

First, set the purchase price to x

Eighty-five percent discount is equivalent to a loss, resulting in a decrease in profits.

20 = get x = 150, the purchase price is 150 yuan, the selling price is 180 yuan, and the number of units is y

y = 300

I was wrong, straight lines do not distinguish between thickness and thickness.

It's a brainteaser.

The plateau is 10,000 square kilometers.

10,000 square kilometers of mountainous terrain.

The plain is 1.8 million square kilometers.

The basin covers 10,000 square kilometers.

Ten thousand square kilometers of hills.

Peking University Jade Bird Tangcheng Campus: Just use 960 times a percentage.

2x+3y=10>=2 root number (2x 3y), so xy<=25 6, if and only if 2x=3y=5 take the equal sign;

lgx+lgy=lg(xy)<=lg(25 6) is the maximum.

Knowing that they are co-circular, let the large radius be r, the small radius is r, the distance from the center of the circle o to the side of the small octagon is h, and the distance to the large is h, then x=h-h, by s large s small = (8*1 2*r 2*sin45°) (8*1 2*r 2*sin45°) = (r r) 2=5000 3200

r r=5 4, from the similarity to h h=r r=5 4, i.e., x=h 4, and 10 h=, h=10(1+ 2), so x=5(1+ 2) 2

Large octagon side length = (5000 3200) * 20 = 25cm; isosceles trapezoidal area (5000-3200) 8=225cm2; x=225*2/(20+25)=10cm;The first one represents the root number, and the other represents the division sign.

Doing it, wait for you to give you the answer.