X2 + 3x-8 = 0 find 1 out of X-2 times x + 1 out of x2-4x + 4 minus x + 2 out of 1

X2 + 3x-8 = 0 find 1 out of X-2 times x + 1 out of x2-4x + 4 minus x + 2 out of 1

x^2+3x-8=0
x=(-3+√9+4*1*8)/2=(-3+√41)/2
Or x = (- 3 - √ 9 + 4 * 1 * 8) / 2 = (- 3 - √ 41) / 2
X-2:1 times x + 1:x2-4x + 4 minus x + 2:1
＝1/(x-2) * (x^2-4x+4)/(x+1) -1/(x+2)
＝ (x-2)^2/(x+1)(x-2) -1/(x+2)
＝ (x-2)/(x+1) -1/(x+2)
＝ ((x-2)(x+2)-(x+1)) /(x+1)(x+2)
＝ (x^2-4-x-1) /(x^2+3x+2)
＝ (x^2-x-5) /(x^2+3x+2)
＝ (x^2-x-5) /(x^2+3x+2)
＝ (8-3x-x-5) /(8+2)
＝ (3-4x) /10
When x = (- 3 + √ 41) / 2
The above formula = (3-4 * (- 3 + √ 41) / 2) / 10
　　＝(-3+6-2√41)/10
　　＝(3-2√41)/10
When x = (- 3 - √ 41) / 2
The above formula = (3-4 * (- 3 - √ 41) / 2) / 10
　　＝(-3+6+2√41)/10
　　＝(3+2√41)/10

The first question: Y2 of X + y + X-Y; the second question: x2-3x + 1 of 2 + x2-5x + 1 of 6 + x2-4x + 1 of 3; the third question: 1-x: 1 + 1 + X: 1 + 1 + X: 2 of 2 + 1 + X: 4; the fourth question: m-2 = m + 2 of () plus points
The first question: Y2 of X + y + X-Y; the second question: x2-3x + 1 of 2 + x2-5x + 1 of 6 + x2-4x + 1 of 3; the third question: 1-x: 1 + 1 + X: 1 + 1 + X: 2 of 2 + 1 + X: 4; the fourth question: m-2 = m + 2 of () plus points

1
x+y+y²/(x-y)
=[(x+y)(x-y)+y²]/(x-y)
=[x²-y²+y²]/(x-y)
=x²/(x-y)
two
1/(x²-3x+2)+1/(x²-5x+6)+1/(x²-4x+3)
=1/[(x-1)(x-2)]+1/[(x-2)(x-3)]+1/[(x-1)(x-3)]
=[(x-3)+（x-1)+（x-2)]/[(x-1)(x-2)(x-3)]
=(3x-6)/[(x-1)(x-2)(x-3)]
three
1/(1-x)+1/(1+x)+2/(1+x²)+4/(1+x^4)
=[(1+x)+(1-x)]/[(1-x)(1+x)]+2/(1+x²)+4/(1+x^4)
=2/(1-x²)+2/(1+x²)+4/(1+x^4)
=2[(1+x²)+(1-x²)]/(1-x^4)+4/(1+x^4)
=4/(1-x^4)+4/(1+x^4)
=4[(1+x^4)+(1-x^4)]/(1-x^8)
=8/(1-x^8)
four
m-2=(m²-4)/(m+2)

1-2 + 3-4 + 5-6 + 7-8 + 9-10. - 2001 + 2002?
I want formulas, not numbers

Don't bind all sequences to formulas
The sequence of numbers is just a Brain Twister
The adjacent odd and even sum is - 1
N{n+（-（n+1））}=-1*N =-1001 N=2002/2

The square of 102 - the square of 99 is calculated by the complete square formula
There is no time
You have to help me in an hour

102 squared - 99 squared
=(102+99)(102-99)
=201×3
=603;
I'm very glad to answer your questions. Skyhunter 002 will answer your questions
If you don't understand this question, you can ask,

The first volume of junior high school
Two manufacturers in Beijing and Shanghai produce computers of the same model at the same time, except for local use. Beijing can transfer 10 computers to other places, Shanghai can transfer 4 computers to other places, and now it is agreed to transfer 6 computers to Wuhan and 8 computers to Chongqing. The freight of each computer is shown in the table below. There is an existing transportation scheme, and the estimated freight is 7600 yuan. In this transportation scheme, Beijing and Shanghai should be transferred to Wuhan respectively, How many in Chongqing
Wuhan Chongqing
Beijing 400 yuan 800 yuan
Shanghai 300 yuan 500 yuan
Set up Beijing to Wuhan x station, Shanghai to Wuhan y station (next)

According to the meaning of the title:
x+y=6 ①
400x+300y+(10-x)800+(4-y)500=7600
400x+300y+8000-800x+2000-500y=7600
-400x-200y=-2400
400x+200y=2400
2x+y=6 ②
② - 1 is x = 0
Substituting x = 0 into (1) yields y = 6

The average of data 58, 57, 42, 45, 50, 54 is______ The median is______ ．

(1) (58 + 57 + 42 + 45 + 50 + 54) △ 6, = 306 △ 6, = 51; (2) the order from small to large is: 42, 45, 50, 54, 57, 58; the median is: (54 + 50) △ 2, = 104 △ 2, = 52; so the answer is: 51, 52

How to write a composition?

It depends on what you feel. The process is as follows: first, write what makes you feel touched, then write what you associate with it, then write your feelings or feelings, and finally summarize the full text

Biology is the teacher of human beings

This article can be written from many angles, such as the Enlightenment from the extinction of animals and plants, or the Enlightenment from the ecological evolution, or the technological progress brought about by bionics. I think it's better, easy to write, and easy to grasp. What's the following
Since ancient times, nature has been the source of all kinds of technological ideas, engineering principles and major inventions of human beings. After a long period of evolution, a wide variety of organisms have been able to adapt to the changes of the environment, so that they can survive and develop. Labor has created human beings. With their upright bodies, hands that can work, language that can exchange emotions and ideas, in the long-term production practice, It promotes the development of the nervous system, especially the brain. Therefore, the unparalleled ability and wisdom of human beings far exceed all groups in the biological world. Through labor, human beings use intelligent intelligence and dexterous hands to make tools, so as to obtain greater freedom in nature. Human intelligence does not only stay in observing and understanding the biological world, Fish have the ability to come and go freely in the water, so people imitate the shape of fish to build ships, and use wooden oars to imitate fins. It is said that as early as the period of Dayu, people in ancient China moved people to observe fish swimming and turning in the water with the swaying of their tails, Through repeated observation, imitation and practice, they gradually changed the oar and rudder to increase the power of the boat and master the means to make the boat turn. In this way, even in the rolling river, people can make the boat sail freely
According to Han Feizi, Luban used bamboo and wood as a bird to "fly for three days". However, people prefer to imitate the bird's wings to fly in the air. As early as 400 years ago, Italian Leonardo da Vinci and his assistants dissected the bird carefully, We have studied the body structure of birds and observed their flight carefully. We have designed and built a flapping wing aircraft, which is the first man-made aircraft in the world
The invention and attempt of imitating biological structure and function can be regarded as the pioneer of human bionics and the sprout of bionics
Although human bionic behavior has been in its infancy for a long time, before 1940s, people did not consciously regard biology as the source of design ideas and inventions. Scientists' research on biology only focuses on describing the delicate structure and perfect function of organisms. Engineers and technicians rely more on their excellent wisdom and hard work, They seldom consciously learn from the biological world. However, the following facts can show that some problems people encounter in technology have appeared in the biological world millions of years ago, and have been solved in the process of evolution. However, human beings have not got the Enlightenment from the biological world
During the first World War, for the sake of military needs, submarines were made for the purpose of making ships navigate under water. When engineers and technicians designed the original submarines, they first installed stones or lead blocks on the submarines to make them sink. If they needed to rise to the surface, they would throw away the stones or lead blocks they carried to make the submarines return to the surface, In order to change the weight of the submarine, the pontoon was alternately filled with water and drained. Later, it was changed into ballast tank. The upper part of the tank was equipped with a vent valve, and the lower part was equipped with a water injection valve. When the tank was filled with sea water, the weight of the boat increased and it dived into the water. When it needed to dive in an emergency, there was also a fast diving tank, If one part of the ballast tank is filled with water and the other part is empty, the submarine can be in a semi submersible state. When the submarine wants to float, the compressed air is introduced into the tank to discharge the sea water, After the weight of seawater in the boat is reduced, the submarine can float up. Such a superior mechanical device enables the submarine to sink and float freely. However, it was later found that the sinking and floating system of fish is much simpler than that of people's invention. The sinking and floating system of fish is only an inflatable swim bladder, which is not controlled by muscles, However, it is too late for the submarine designers to inspire and help with the ingenious sinking and floating system of fish
Sound is an indispensable element in people's life. Through language, people exchange ideas and feelings. Beautiful music makes people enjoy art. Engineers and technicians also apply acoustic system in industrial production and military technology, which has become one of the most important information, What follows is how the surface ships find out the position of submarines to prevent sneak attacks. After the submarines sink into the water, they also need to accurately determine the orientation and distance of enemy ships to facilitate attacks, Naval engineers also use acoustic system as an important means of reconnaissance. First of all, they use hydrophone, also known as noise direction finder, to find the enemy ship by listening to the noise emitted by the enemy ship during navigation. As long as there is an enemy ship sailing in the surrounding waters, the machine and propeller will emit noise, But at that time, the hydrophone was very imperfect. Generally, it could only receive the noise of its own ship. To listen to the enemy ship, it was necessary to slow down the ship's speed or even stop completely to distinguish the noise of the submarine, which was not conducive to combat action, French scientist Langevin (1872-1946) has successfully used the nature of ultrasonic reflection to detect underwater ships. An ultrasonic generator is used to send ultrasonic waves into the water. If it meets the target, it will be reflected back and received by the receiver. According to the time interval and azimuth of the received echoes, the azimuth and distance of the target can be measured, This is the so-called sonar system. The invention of man-made sonar system and its outstanding achievements in reconnaissance of enemy submarines have made people marvel at it. Do you know that bats and dolphins had already applied echolocation sonar system before human beings appeared on the earth
Bats can "see" with their ears and mouths
For a long time, creatures lived in the nature surrounded by sound. They used sound to seek food, escape from enemies and mate. Therefore, sound is an important information for living creatures. Spalanger, an Italian scientist, discovered long ago that bats can fly freely in complete darkness, avoid obstacles and prey on flying insects, In the face of these facts, spalanger put forward an unacceptable conclusion: bats can "see" with their ears and mouth. They can send out ultrasonic waves with their mouths and receive them with their ears when they touch obstacles and reflect them back. After the end of World War I, in 1920, after the end of World War II, the bat can see with their ears, Hatai thinks that the frequency of the sound signal emitted by bats is beyond the range of human hearing, and proposes that the method of locating the target by bats is the same as the method of locating the target by ultrasonic echo invented by Lang Zhiwan in the first World War, It was not until 1983, when an electronic measuring device was used, that it was completely confirmed that bats were located by sending out ultrasonic waves. However, this was not helpful to the early invention of radar and sonar
The Enlightenment of dragonfly's wings on aircraft building
Another example is people's understanding of insects