About "0"

0, can be said to be the earliest human contact number. Our ancestors only knew nothing and existence at first, and none of them was 0, so 0 isn't it? I remember the primary school teacher once said, "Any number minus itself is equal to 0, and 0 means there is no number." This statement is obviously incorrect. As we all know, 0 degrees Celsius on the thermometer indicates the freezing point of water (that is, the temperature of ice-water mixture at standard atmospheric pressure), where 0 is the distinguishing point between solid and liquid water. Moreover, in Chinese characters, 0 means more as zero, such as: 1) fragmentary; A small part. 2) The quantity is not enough for a certain unit ... At this point, we know that "no quantity is 0, but 0 not only means no quantity, but also means the difference between solid and liquid water, and so on."

"Any number divided by 0 is meaningless." This is a "conclusion" about 0 that teachers from primary school to middle school are still talking about. At that time, division (primary school) was to divide a copy into several parts and figure out how many there were in each part. A whole cannot be divided into 0 parts, which is "meaningless". Later, I learned that 0 in a/0 can represent a variable with zero as the limit (the absolute value of a variable is always smaller than an arbitrarily small positive number in the process of change) and should be equal to infinity (the absolute value of a variable is always larger than an arbitrarily large positive number in the process of change). From this, another theorem about 0 is obtained: "A variable whose limit is zero is called infinitesimal".

"Room 203 105 in 2003", although all of them are zeros, they are roughly similar in appearance; They have different meanings. 0 indicator vacancy of 105 and 2003 cannot be deleted. 0 in Room 203 separates "Building (2)" from "House Number". (3) "(that is, Room 8 on the second floor) can be deleted. 0 also means that ...

Einstein once said: "I always think it is absurd to explore the meaning and purpose of a person or all living things." I want to study all the numbers of "existence", so I'd better know the number of "non-existence" first, so as not to become what Einstein called "absurd". As a middle school student, my ability is limited after all, and my understanding of 0 is not thorough enough. In the future, I hope (including action) to find "my new continent" in the "ocean of knowledge".

Mathematics in life

There is a riddle: there is something invisible and intangible, but it is everywhere. What is this? The answer is: air. And mathematics, like air, is invisible and intangible, but it exists all the time around us.

Wonderful "golden numbers"

Take a line segment, find a point on the line segment, and let this point divide the line segment into two parts, one is long and the other is short, and the ratio of long segment to short segment is exactly equal to the ratio of whole segment to long segment. This point is the golden section of this line segment. This ratio is: 1: 0.6 18… and 0.6 18… This number is called "golden number".

Interestingly, this number can be seen everywhere in life: the navel is the golden section of the total length of the human body; The angle between two adjacent leaves on the stems of some plants is exactly the angle between the two radii that divide the circumference into 1: 0.6 18 …. According to research, this angle has the best effect on ventilation and lighting of the factory building.

Architects especially prefer the number 0.6 18 ... Whether it is the pyramids of ancient Egypt, Notre Dame de Paris or the modern Eiffel Tower, the number 0.6 18 ... It is also found that most of the subjects of some famous paintings, sculptures and photography are at the 0.618 ... Musicians believe that putting the bridge at 0.618 of the strings will make the sound softer and sweeter.

The number 0.6 18… also makes the optimization method possible. Optimization method is a method to solve the optimization problem. If it is necessary to add a chemical element to increase the strength of steel during steelmaking, it is assumed that the amount of a chemical element to be added per ton of steel is between 1000-2000g. In order to find the most suitable dose, we usually take the midpoint of the interval for experiments, and then compare it with the experimental results of 1000 g and 2000 g respectively, select two points with higher intensity as the new interval, and then take the midpoint of the new interval for experiments until the most ideal effect is obtained. However, this method is inefficient. If the measuring point is taken at the interval of 0.6 18, the efficiency will be greatly improved. This method is called "0.6 18 method". Practice has proved that the former method can be realized by using "0.6 18 method" to test 16.

There are so many examples and applications of "golden number" in life. Perhaps, there are more mysteries waiting for us to explore, so that it can serve us better and solve more problems for us.

Wonderful axial symmetry

If a straight line can be found on a graph, the graph can be aligned along this straight line, so that the two sides can completely overlap. Such a figure is called an axisymmetric figure, and this straight line is called an axis of symmetry.

Careful observation shows that the plane is a standard axisymmetric object. Looking down, its wings, fuselage and tail are all symmetrical. Axial symmetry makes its flight more stable. If the plane is not axisymmetric, it will fly stagger. At that time, who wanted to fly?

Looking closely, it is not difficult to find that many works of art are also axisymmetric. Take the simplest example: the bridge. It is the most common work of art in life. Take the bridges in Jinhua as examples: Tongji Bridge, Jinhongqiao, Shuanglong Bridge and Riverside Bridge. They are all axisymmetric. The ancient buildings in China are even more obvious. Ancient palaces were basically symmetrical. Another famous: the layout of Beijing. This is the most typical axisymmetric layout. It is symmetrical with the Forbidden City, Tiananmen Square, Monument to the People's Heroes and Qianmen as the central axis. The application of axial symmetry in art can make art look more beautiful.

Axisymmetry is also a biological phenomenon: human ears, eyes and limbs all grow symmetrically. The axial symmetry of the ear makes the sound we hear have a strong three-dimensional sense and can also determine the position of the sound source; The symmetry of the eyes allows us to see objects more accurately. It can be seen that our life is inseparable from axial symmetry.

Mathematics is very close to us, and it is reflected in all aspects of life. We can't live without mathematics, which is everywhere. These are just two very common examples, and there are countless such examples. I think mathematics in life can bring more discoveries to people.

But now I guess it's useless. There are so many words to write at this point.