(2900-x-2500) (8 + 4x / 50) = 5000

（400-x）=40000+400x
-401x=40000-400
-401x=39600
x=-39600/401

Subtract 5 out of 8 from a number to get 2 out of 7

Let this number be x, then we have:
x-5/8=2/7;
x=5/8+2/7
x=35/56+16/56
x=51/56;
If you don't understand this question, you can ask,

Why dy / DX = u + Du / dy?
Sorry for the wrong input. Why should it be dy / DX = u + X * Du / dy?

U is also a function of X
So dy / DX = u + XDU / DX

2,6,13,39,15,45,23,()
What should be filled in the brackets?

It should be 69, because in this question, 2 and 6 are three times the relationship, 13 and 39 are three times the relationship, 15 and 45 are three times the relationship

The ratio of class 6 (1) to class 6 (2) is 8:7. If 8 students in class 6 (1) are transferred to class 6 (2), the ratio of class 6 (1) to class 6 (2) becomes 4:5?

A: there were 48 students in class one and 42 students in class two

The projection curve of the intersection of surface x ^ 2 4Y ^ 2 Z ^ 2 = 4 and plane x z = a on xoy plane is
Attachment: 2, 1-1 / 2! + 1 / 3! - 1 / 4! + 1 / 5! - 1 / 6! + =（）
The first one is x ^ 2 + 4Y ^ 2 + Z ^ 2 = 4, I have the wrong number

1. Can't it be the wrong number? This If x ^ 2 (4Y) ^ 2Z ^ 2 = 4 intersects with XZ = a, the intersection is y = 1 / 2a and y = - 1 / 2A. These two lines are projection lines
2. This Because I am a college student, I use Taylor expansion; because e ^ (- t) = 1-T + T ^ 2 * 1 / 2! + T ^ 3 * 1 / 3! + So the original formula = 1-e ^ (- 1) = 1-1 / E

What are the differences and similarities between zero water and zero ice

They have the same degree of cold and heat, that is to say, they are the same cold. Because the temperature represents the degree of cold and heat of objects. The same temperature means the same degree of cold and heat
But their cooling effect is not the same, ice cooling effect is good, because zero degree ice melts into zero degree water to absorb heat

What unit of physical quantity can "H" stand for in physics? (for example, what does mm / h stand for?)
What unit of physical quantity can "H" represent in physics?
What does mm / h stand for

Time unit, one hour per millimeter

How to convert LG to log? How to convert 1.02 to LG?

The difference between LG and log is that LG is the logarithm with the base of 10, that is log10a = LGA (LG is the abbreviation of log10)
Use the formula to convert, such as: lognb = LGB / LGN
Let 1.02 ^ 20 = m, then the logarithm (LG) on both sides has, lg1.02 ^ 20 = LGM, that is
20lg1.02=lgm
20=lgm/lg1.02
20 = log1.02m (logarithm based on 1.02)

The place where longitude and latitude are both 0 degrees is located in () A. Eastern Hemisphere B. Western Hemisphere C. southern hemisphere D. northern hemisphere
Try to be more detailed so that I can understand,

A. Eastern Hemisphere
The dividing line between the eastern and western hemispheres is 20 degrees west longitude and 160 degrees east longitude. The 0 degree longitude is to the east of 20 degrees west longitude, so it is located in the eastern hemisphere
The dividing line between the northern and southern hemispheres is the 0 degree latitude, so the 0 degree latitude is neither in the southern hemisphere nor in the northern hemisphere

(2900-x-2500) (8 + 4x / 50) = 5000