A cylinder, the side is a square, its side length is 18.84 cm, the bottom radius of the cylinder is______ ．

18.84 △ 3.14 △ 2 = 3 (CM), answer: the bottom radius of the cylinder is 3cm

It takes a few minutes for the sun to shine on the earth

Light speed v = 3 000 km / S (km / s)
The distance from the sun to the earth is s = 1 500 km
Find H
h=s/v
h=15 0 0 0 0 0 0 0/3 0 0 0 0 0
H = 1500 / 3 = 500 (seconds)
H = 8.3333 (min) is about 8 minutes
A: it takes about eight minutes for the sun to shine on the earth

A physical calculation of power,
1. If an object with a mass of 2kg is placed on the horizontal ground with a sliding friction coefficient of μ = 0.2, the speed of the object increases from 3m / s to 4m / s in the fourth second under the action of the horizontal constant force. Find: (1) the average power of the horizontal constant force in this second; (2) the power of the horizontal constant force at the end of the fourth second

The acceleration is 1 m / S ^ 2, the resultant force is 2 N, and the friction force is 4 N, so the constant force is 6 n. The average velocity in this second is 3.5 m / s, and P = FV, we can know that P = 6 * 3.5 w = 21 W. similarly, the velocity at the end of 4 seconds is 5 m / s, and the power is p = 4 * 6 w = 24 W

The perimeter of the two squares differs by 16 cm and the area by 96 square cm. How many cm are the sides of the two squares?
No equations, just formulas. I know they are 10 cm and 14 cm respectively

Drawing is more intuitive
The big one has two more small rectangles and a small square than the small one. If the side length of the small square is 4 and the area is 16, then the area of the small rectangle is 1 / 2 (96-16) = 40, and the width is 4, so the length is 10. That is to say, the side length of the small square is 10, and the big one is 4

Calculation: 20 + 19-18-17 + 16 + 15-14-13 + +4+3-2-1．

20+19-18-17+16+15-14-13+… +4+3-2-1，=（20-18）+（19-17）+（16-14）+… +（4-2）+（3-1），=2+2+2+2+2+2+2+2+2+2，=2×10，=20．

Given the function f (x) = | x | / x + 2, find the range of F (x) Detailed steps

f(x)=|x|/(x+2)
When x > 0, f (x) = x / (x + 2) = 1 - 2 / (x + 2)
0

On a rectangular grassland with length of AM and width of BM, there is a curved path. The left line of the path is shifted 1m to the right, which is its right line
On a rectangular grassland with length of AM and width of BM, there is a curved path. The left line of the path is shifted 1m to the right, which is his right line. The green area of this grassland is calculated
I haven't thought about it for a long time. For example, I want to find two ropes (as a path). One is longer than the other, and the short one is straight there. The other one bends it to be the same length as the short one. The area of these two ropes is obviously different
I know the answer is ab-b, but why?

If the path goes from one long side to the other
The actual length of grassland is shortened by 1 m because of 1 m translation
Area = (A-1) * b = ab-b M2
If the path goes from one short side to the other
In the same way, the actual width of grassland is shortened by 1m
Area = a * (B-1) = AB-A square meter
PS: you misunderstand the meaning -- "think of a curved road as a straight road on the edge of the vertical grass, the width of the road is 1m"!

Grade 7 Volume 1 answers to math homework page 1 18

Each place's exercise book is different, and it may not be right to send it to you

In known sequence, A1 = 2, an = 2A (n-1) + 3 (n ≥ 2, n ∈ n), find an

An=2A（n-1）+3
Then an + 3 = 2A (n-1) + 6
That is, an + 3 = 2 [a (n-1) + 3]
Therefore, an + 3 is an equal ratio sequence with the first term a1 + 3 = 5 and the common ratio of 2
An+3=5*2^(n-1)
So an = 5 * 2 ^ (n-1) - 3

A house needs to be paved with square bricks. It needs 270 square bricks with an area of 0.16 square meters. If it is replaced with square bricks with a side length of 0.3 meters, how many such bricks are needed?

If we use the square brick with side length of 0.3m, we need x pieces; if we use the square brick with side length of 0.3m, we need 480 pieces; if we use the square brick with side length of 0.3m, we need 480 pieces; if we use the square brick with side length of 0.3m, we need 480 pieces

A cylinder, the side is a square, its side length is 18.84 cm, the bottom radius of the cylinder is______ ．