The circumference of a cuboid is 80cm, and the ratio of length to width is 4:1. What's the area of the cuboid? Tao Jie and Jiang Tao travel from a to B at the same time, and their speed ratio is 4:3. Tao Jie travels 20 kilometers per hour, and Jiang Tao travels how many kilometers per hour?

The circumference of a cuboid is 80cm, and the ratio of length to width is 4:1. What's the area of the cuboid? Tao Jie and Jiang Tao travel from a to B at the same time, and their speed ratio is 4:3. Tao Jie travels 20 kilometers per hour, and Jiang Tao travels how many kilometers per hour?

1. Length is 80 / 2 * 4 / (4 + 1) = 32, width is 80 / 2-32 = 8, area is 32 * 8 = 256
20 * 3 / 4 = 15, Jiang Tao travels 15 kilometers per hour

1 minute to answer math questions
If | a + B | = - (a + b), the following conclusion is correct ()
A. A + B is less than or equal to 0 B. A + B is less than 0 C. A + B is equal to 0 d. A + B is greater than 0

Replace a + B with X
That is | x | = - X
x

Kneel down to find the general formula of 1 / (2 * 3), - 2 / (3 * 4), 4 / (4 * 5), - 8 / (5 * 6)

(-2)^(n-1)/[(n+1)*(n+2)]
Well, I'll talk about my ideas. It's been a long time. Everything I learned before has been returned to my teacher (er That's it.)
The sign of single and even numbers can be seen as (- 1) ^ (n-1)
After that, the molecule is 2 ^ (n-1)
Look at the denominator again
Number of items 1 2 3 4 n
(2,3) (3,4) (4,5) (5,6) we can see that (n + 1) (n + 2)
That is 1 / [(n + 1) (n + 2)]
And then we put it all together
(-2)^(n-1)/[(n+1)*(n+2)]

When was the electronic cloud structure of atoms proposed?

In 1926, Austrian scholar Schrodinger put forward the famous Schrodinger equation of second-order partial differential on the basis of debroy relation. The solution of this equation, if expressed graphically in three-dimensional coordinates, is the electron cloud
Please refer to inorganic chemistry, edited by Department of inorganic chemistry, Beijing Normal University, 1981 edition, published by people's education press

Do you know the difference between acetic acid and glacial acetic acid?

Acetic acid is also called glacial acetic acid. Acetic acid can form ice like solid below 16.6 ℃, so it is often called glacial acetic acid

What is the formula of mass in physics?

1. Mass = density * Volume
2. Mass = gravity / g
3. Kinetic energy = mass * velocity squared / 2
There are many formulas related to quality, which are not listed

Kneeling for LN addition, subtraction, multiplication and division algorithm
It is similar to ln2-ln1 / 2 = LN2 - (- ln1-ln2) = LN2 + LN2 = 2ln2 addition?

LN2 + ln1 / 2 = ln (2 * 1 / 2) = ln1 = 0, LN2 / ln1 / 2 = Log1 / 2 (base number) 2 (true number) = - log2 2 = - 1,

Which direction is 170 degrees east longitude at 160 degrees west longitude
East or west

170 east longitude, 160 west longitude
The judgment of the east-west direction of the earth's surface is generally based on the rotation direction as the reference when the longitude difference between the two places is less than 180 degrees
The difference between east longitude 170 and west longitude 160 is less than 180. Therefore, east longitude 170 is to the west of west longitude 160

Is 0 a natural number? Does zero in three make sense?

In the past, 0 was not regarded as a natural number. Now it is regarded as a natural number. Zero thirds has its mathematical meaning, at least it is a real number in the mathematical sense

Combined with the image, find the image of the root of the equation SiNx = x, draw two graphs, y = SiNx, y = x, the number of focus is the number of solutions, how to list to draw a picture

This drawing is not accurate,
Using trigonometric function line
At (0, π / 2), SiNx