A cylindrical paper tube is a square with its side expanded. It is known that the bottom area of the cylinder is 5 square decimeters. What is its surface area? 2. The distance between a and B is 10000 kilometers. A rides a bicycle and B walks. At the same time, from a to B, the speed of a is four times faster than that of B. on the way, a's bicycle breaks down and the repair of the car is delayed for some time. So when B arrives at B, a is 200 meters away from B. how many meters does a repair the car and B walk? There are two bags of rice. The original ratio of rice to grain in the two bags is 12:7. After taking 10 kg from the first bag and putting it into the second bag, the first bag is 1 and 1 / 9 times as much as the second bag. How many kg of rice are there in the first bag? The average score is 9.64 after removing the highest score and the lowest score. The average score is 9.72 after removing the lowest score. The average score is 9.61 after removing the highest score Ancient arithmetic: today there are five cattle and two sheep, which are worth ten liang of gold; two cattle and five sheep, which are worth eight liang of gold. How much gold are cattle and sheep worth? It is 108 meters long from one end of the playground to the other end. A red flag is inserted every 4 meters on one side of the playground and at both ends. Now, a red flag is inserted every 6 meters. How many sides (including the two sides of the end) can be left out? How many sides need to be pulled out?

1. According to the condition that the side expansion is a square, C = h, side area = ch = CC = 2 π R × 2 π r = 4 × π × π RR = 4 × 3.14 × 5 = 62.8 square meters
Surface area = 62.8 + 5 × 2 = 72.8 square meters
2. The speed ratio is 4:1, and the distance ratio at the same time is 4:1. A runs a total of 9800 meters. If a doesn't repair the car, B runs 9800 △ 4 = 2450 meters, but B completes the whole journey. Therefore, when a repairs the car, B runs 10000-2450 = 7550 meters
3. The ratio of two bags of rice to grain is 12:7, which means that the first bag accounts for 12 / 19 of the total number of the two bags; the first bag is 1 / 9 times of the second bag, which means that the first bag accounts for 10 / 19 of the total number of the two bags, and the total number of the two bags does not change, so the less 2 / 19 is the 10kg taken out, and the total number of the two bags is 10 △ 2 / 19 = 95kg, 95 × 12 / 19 = 60kg
4. 64 × 3 = 28.92, 9.72 × 4 = 38.88, 9.61 × 4 = 38.44, the highest score is 38.88-28.92 = 9.96, the total average is (38.44 + 9.96) △ 5
5. Niuwu, Yanger, is worth ten taels of gold, that is, niu10, yang4, is worth 20 taels (double). Similarly, Niuer, yang5, is worth eight taels of gold, that is, niu10, yang25, is worth 40 taels (5 times). The difference of 20 taels is the money of 21 sheep, 20 △ 21 for each sheep, and (10-2 × 20 / 21) △ 5 for each cattle
6. The flag on the common multiple of 4 and 6 does not need to be drawn, which is also 108 ／ (4,6) = 108 ／ 12 = 9,9 + 1 (the first side) = 10, and the plane does not need to be drawn; 108 ／ 4 + 1-10 is the one to be drawn
I'm so tired. Give me more points!

A and B two opposite trains meet on the way. The driver of car a sees car B passing by and takes 6 seconds. It is known that car a travels 13 meters per second and car B 12 meters per second. How long is car B?

(13 + 12) * 6 = 150 (m) because car B drives by the driver of car a, 6 seconds is the distance between the two cars, which is the length of car B and the problem of meeting, so speed and * meeting time = meeting distance (car B's length)

It is proved that the cubic power of function y = x [x belongs to R] is an increasing function?
Let X1 be less than x2. Why is it greater than zero

Because the square of a number is greater than or equal to 0, so [the square of (x1 + Half x2) + the second power of three fourths x2] is greater than or equal to 0, and this formula is equal to 0 only when X1 and X2 are both 0. Because X1 is less than x2, this formula can only be greater than 0

How many square meters is 270 square decimeters

1 square decimeter = 0.01 square meter
So 270 square decimeters = 270 * 0.01 = 2.7 square meters

If a times B is greater than 0, then the absolute value of a divided by a + B divided by B + a times b divided by a times B is?

If a times B is greater than 0, a and B have the same sign,
When a and B are both positive numbers, | a | / A + B / | B | + AB / | ab | = 1 + 1 + 1 = 3
When a and B are both negative numbers, | a | / A + B / | B | + AB / | ab | = - 1-1 + 1 = - 1

Find the derivative implicit function x / y + √ (Y / x) = 1 sin (XY) - ln [(y + 1) / y] = 1, find y '(0)
Derivative implicit function x / y + √ (Y / x) = 1
Sin (XY) - ln [(y + 1) / y] = 1, find y '(0)

X / y + √ (Y / x) = 1, both sides of X are derived: (y-xy ') / y ^ 2 + 1 / [2 √ (Y / x)] * (y'x-y) / x ^ 2 = 02x ^ 2 (y-xy') + y ^ 2 (XY '- y) / √ (Y / x) = 0, so only y-xy' = 0 can be obtained, and y '= Y / X can be obtained

Calculation: 3.49 + 4.47 + 3.51-2.38 + 4.53-2.62=______ ．

3.49 + 4.47 + 3.51-2.38 + 4.53-2.62 = (3.49 + 3.51) + (4.47 + 4.53) - (2.38 + 2.62) = 7 + 9-5 = 11

50 is 10 less than two fifths of a number. Find the number

Let this number be X
2/5x -10 =50
2/5x =60
X = 60 divided by 2 / 5
X = 60 times 5 / 2
x= 150

If the minimum value of quadratic function f (x) = x square - ax + A / 2 (a is greater than 0) in the interval [0,1] is g (a), the minimum value of G (a) can be obtained

The symmetry axis of F (x) = x ^ 2-ax + A / 2 is: x = A / 2
1) When a / 2 > 1, that is, when a > 2, G (a) = f (1) = 1-A + A / 2 = 1-A / 2

How to calculate 9 out of 13 + 5 out of 7-8 out of 13 + 2 out of 7?

9 / 13 + 5 / 7-8 / 13 + 2 / 7
=(9 / 13-8 / 13) + (5 / 7 + 2 / 7)
=1 / 13 + 1
=1 and 1 in 13