Who can tell me the strict definition of various numbers in mathematics, such as rational number, imaginary number, natural number and so on

Rational numbers, positive integers 0, negative integers are collectively referred to as integers. Positive fractions and negative fractions are collectively referred to as fractions. Integers and fractions are collectively referred to as rational numbers, irrational numbers, wireless non cyclic decimals are called irrational real numbers, rational numbers and irrational numbers are collectively referred to as real numbers. Natural numbers are numbers greater than zero, excluding decimals. Imaginary numbers, negative numbers squared, no solution in the range of real numbers

Concepts of natural number, integer and rational number

Natural numbers are integers without negative numbers, that is, 0 and positive integers (such as 0, 1, 2,...)
An integer is a number that has zero decimal places, that is, a number that can be divided by 1 (such as - 1, - 2,0,1,...) .
Rational number is only limited decimal (can be zero) or infinite circular decimal (such as 1,1.42,3.5,1 / 3,0.77777 ,……） .

A problem of inequality system
Make up a practical problem about x + 6 > 0

Given that the sum of real number x and 6 is positive, find the range of X
x+6>0
The range of X is: x > - 6

1. Both passenger and freight cars leave from a and B at the same time. Freight cars travel 42 kilometers per hour and passenger cars 54 kilometers per hour,
How many kilometers is the distance between a and B?
2. For a road, the ratio of the repaired to the unmodified is 1:5. For another 50 meters, the ratio of the repaired to the unmodified is 3:5. How long is the road?

1. Distance between a and B: (42 + 54) x3 △ 3 / (3 + 2) = 480 (km)
2. If the road is x meters long, it can be obtained according to the meaning of the title
50/x=1/5-5/8,
The solution is x = 2000
So this road is 2000 meters long

The central projection of Mathematics
Xiao Ming has a 2-meter-long bamboo pole. He wants to measure the height of a street lamp in front of his house, but he can't measure it directly. He uses the following methods: 1. One night, he goes to a place next to the street lamp, puts the bamboo pole upright, and measures the shadow length of 1 meter. 2. Xiao Ming walks 4 meters in the distance along the direction of the shadow of the bamboo pole, Then he put up a bamboo pole to measure the shadow length of 2 meters. How did Xiao Ming calculate the height of the street lamp?

1. One night, he went to a place beside the street lamp, put the bamboo pole upright, and measured the shadow length of 1 meter. At this time, the shadow of the bamboo pole was not half the distance from the end to the lamp. 2. Xiao Ming walked 4 meters along the direction of the shadow of the bamboo pole, and then put up the bamboo pole to measure the shadow length of 2 meters

The original number ratio of team a and team B is 7:3. After transferring some people from team a to team B, the number ratio of team a and team B is 3:2. Team B has 120 people and team B has several

90 people

There is a natural number n, and both N and N + 2004 are square numbers. What is n?

N=A²
N+2004=B²
subtract
B²-A²=2004
(B+A)(B-A)=2*1002
B+A=1002
B-A=2
B=502,A=500
N=A²=250000

If a 70 kW truck runs 120 km at a speed of 72 km / h on the highway, it will cost more
I'm not sure. The answer is 5 / 3 350 / 3 35 / 36
How many hours does it take, how much work does it do, and what is the traction force of a 70 kW truck if it travels 120 km at a constant speed of 72 km / h on the highway?

It takes about one hour and thirty-six minutes. How much work you do depends on the weight of your car and the weight of your load. The traction also depends on the weight
by the way
70 kW doesn't seem to be heavy!

If a + X * x = 1991, B + X * x = 1992, C + X * x = 1993 and ABC = 24 A / BC + B / Ca + C / AB - 1 / a - 1 / B - 1 / C

B-A = 1, C-A = 2, C-B = 1. A / BC + B / Ca + C / AB - 1 / a - 1 / B - 1 / C = A / BC + B / Ca + C / AB - B / ab-c / bc-a / Ca = A / bc-c / BC + B / Ca-A / Ca + C / ab-b / AB = (A-C) / BC + (B-A) / Ca + (C-B) / AB = (a (A-C) + B (B-C) + C (C-B)) / ABC = (- 2A + B + C) / ABC = (b

Two cars are running from two places 400 kilometers apart at the same time. Three hours later, they are 10 kilometers apart. It is known that one car runs 55 kilometers per hour. How can we find the speed of the other car? (answer in two ways)

Use the arithmetic method: (400-10) △ 3-55, = 390 △ 3-55, = 130-55, = 75 (km / h); use the equation to set the speed of another car as X km / h, (55 + x) × 3 = 400-10, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 55 + x = 390 △ 3, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 55 + x = 130, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 130-55, & nbsp; &A: the speed of the other car is 75 kilometers per hour

Who can tell me the strict definition of various numbers in mathematics, such as rational number, imaginary number, natural number and so on