1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)+1/(x+4)(x+5)=5/x^2+11x-708

1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)+1/(x+4)(x+5)=5/x^2+11x-708

Answer: split item knowledge of fraction
1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)+1/(x+4)(x+5)=5/x^2+11x-708
1/x-1/(x+1)+1/(x+1)-1/(x+2)+.+1/(x+4)-1/(x+5)=5/(x^2+11x-708)
1/x-1/(x+5)=5/(x^2+11x-708)
(x+5-x)/(x^2+5x)=5/(x^2+11x-708)
5x^2+55x-3540=5x^2+10x
45x=3540
x=236/3
After testing, x = 236 / 3 is the root of the original fractional equation

Equation 26-5x = 100-11x

6x=74
x=74/6
x=37/3

12/11x+120%x=6.5

=(12/11+120%)X=6.5
=(1.091+1.2)X=6.5
=2.291X=6.5
=6.5/2.291=X
x=2.837

The fence around a semicircle flowerbed is 25.7m long. What is the area of the flowerbed

The fence around a semicircle flowerbed is 25.7m long. What is the area of the flowerbed?
Radius 25.7 △ 3.14 + 2) = 25.7 △ 5.14 = 5m
Area: 3.14 × 5 × 5 × 1 / 5 = 39.25 square meters

Exact and its adjectives, nouns, and their usage

It is difficult to prove that the sum of squares of the lengths of two sides of any parallelogram is equal to the sum of squares of the lengths of two diagonals of the parallelogram
It is proved that the sum of squares of the lengths of two sides of any parallelogram is equal to the sum of squares of the lengths of two diagonals of the parallelogram
That is, let the upper left corner of the parallelogram be a, the upper right corner be B, the lower left corner be C, and the lower right corner be D. the four sides are AB, BD, DC, ca. the diagonals are ad, BC
Prove that the square of (AB) + the square of (CA) = the square of (AD) + the square of (BC)
I'm just the first year of junior high school. Help me to say something simple!

You can take a look at the knowledge of vector. Although it is high school knowledge, it is easier to learn than many junior high school knowledge. If you use vector method, it will be the fastest way to solve this problem: the solution is as follows:
1. The title should be 2 (AB) square + 2 (CA) square = (AD) square + (BC) square, that is, the sum of the squares of the four sides is equal to the sum of the squares of the diagonal
2. Right = (AD) squared + (BC) squared
=Square of (Ad vector) + square of (BC vector)
=Square of (ab-ca vector) + square of (AB + Ca vector)
=Square open
=The square of 2 (AB vector) + the square of 2 (CA vector)
=Square of 2 (AB) + square of 2 (CA)
This method is really simple, and it can be extended to any quadrilateral in the same way: a quadrilateral in any plane has the sum of squares of four sides equal to the sum of squares of two diagonals
To learn vector, you should be able to easily understand

The usage of the past tense and the future tense in English

I met him yesterday

1. At 20 ℃, there is 26.4g salt in 100g saturated salt solution, so the solubility of salt at 20 ℃ is 26.4g/100g water
2. At 20 ℃, 10g salt is dissolved in 100g water, so the solubility of salt at 20 ℃ is 20g / 100g water
3. At 20 ℃, the solubility of salt is 36g / 100g water. When 20g salt is put into 50g water, the mass of saturated solution is 68g
This is a multiple-choice question, which of the three options above is right, and explain the reason (why the wrong option is wrong)
When I do this kind of topic, I always don't understand it. My thinking is confused. I want to find a good solution
(try to be concise,

First, the concept of solubility is clarified: solubility refers to the mass of solute dissolved in 100g solvent (usually water)
1. "100g saturated salt solution" contains 26.4g salt, so the solubility of salt at 20 ℃ is 26.4g/100g water
It's not 100 g of water;
2. Let's not talk about that; it's not saturated at all
3. 50g water can hold 18G, 20g salt has 2G undissolved, so 50 + 18 = 68g

Why is the actual resonant frequency of RLC series resonant circuit greater than the theoretical value
Can we consider this problem from the resistance of the inductance coil itself?

You use the nominal value of the component in the theoretical calculation, but in the actual circuit, the actual value of the component is not necessarily the nominal value, so this result is very normal

Expounding the necessity of China's reform and opening up with Marx's basic principles

During the 30 years of reform and opening up, China has made brilliant achievements. It has not only enriched and developed Marxism, but also greatly mobilized the enthusiasm of hundreds of millions of people. As a result, China has successfully realized the great historical turning point from a highly centralized planned economy to a dynamic socialist market economy, and from a closed and semi closed economy to an all-round opening-up, which has greatly liberated the productive forces, Over the past 30 years, China's GDP has increased at an average annual rate of 10%, from 364.52 billion yuan in 1978 to 24661.9 billion yuan in 2007, ranking fourth in the world. The number of rural poor has decreased from 250 million to 20 million, and people's life has developed from insufficient food and clothing to a well-off society
In the final analysis, the achievement of reform and opening up that attracts worldwide attention is the combination of the basic principles of Marxism with China's reality, which is the process of Sinicization of Marxism. According to Marx's principles, reform and opening up has historical inevitability
Let's talk about the inevitability of reform. According to the basic principles of Marxism, the contradiction between productive forces and production relations, economic base and superstructure is the basic contradiction of human society. The movement of this basic contradiction promotes the development of human society. The ultimate root of social development lies in the improvement of productive forces, When the productive forces develop to a certain extent, there will be sharp contradictions with the original production relations. At this time, the production relations will change. Compared with the social superstructure, the production relations are also called the economic foundation, When the economic base needs to be changed or has been partially changed, it conflicts with the original superstructure. This requires the transformation of the superstructure. The so-called economic system reform is to reform the relations of production to adapt to the productive forces, and the so-called political and cultural system reform is to reform the superstructure to adapt to the economic base, In a word, it is the most basic, universal and scientific theory to explain all social changes. The basic contradictions in China's socialist society are still the contradictions between productive forces and production relations, economic base and superstructure. The nature of the basic contradictions in socialist society is non confrontational and can be solved through the self-improvement and development of the socialist system, Only through the reform of the economic system, political system, education, science and technology, and cultural system, can we establish and improve the socialist market economic system, develop socialist democratic politics, and build socialist spiritual civilization, so as to liberate the productive forces bound by the old system, Reform is the fundamental way to solve the basic contradictions of socialist society and the driving force to promote the development of socialist society. Take the reform of rural economic system as an example, changing the people's commune system to the household contract responsibility system greatly liberates the rural productivity, mobilizes the enthusiasm of the farmers, promotes agricultural development and solves the problem of rural constraints
On China's reform and opening up from the Marxist principle of universal connection of things
According to Marxism, the world is a universally connected whole, and there are relationships of mutual influence, mutual restriction and interaction among all elements within and among things. In order to achieve good development, a country or a nation must deal with its internal and external relations well, and constantly deepen its internal reform, In the era of economic globalization, the fact of "global village" is becoming more and more obvious. The interrelationship and interdependence among countries and nationalities are becoming closer and closer. Any country or nation's narcissism and self isolation will only lead to its own backwardness, Only those countries that regard opening up as their basic national policy, invite in and go out, and learn from other countries and nationalities, can seize the opportunity to develop themselves. China's accession to the WTO, absorption of advanced market economy experience, and the recently concluded Olympic Games
According to materialist dialectics, internal cause is the internal contradiction of the development of things, the source of the development of things, and the fundamental reason of the change of things. External cause is the external contradiction of the development of things, and the condition of the development of things, which plays the role of acceleration and delay. External cause must work through internal cause. Internal cause and external cause are relative, and then transform each other under certain conditions, We must attach importance to the role of internal cause, but we can't ignore the role of external cause. When analyzing and solving problems, we should stick to the view of combining internal and external causes
At home, we should always adhere to independence and carry out reform and opening up, because it is a necessary condition for a country to become rich and strong and to ensure independence and democracy. It is the internal cause of national development. Opening up is a major requirement of today's world development trend. Only by better integrating into the world and participating in world competition can we obtain long-term economic benefits, To seek long-term development. Opening to the outside world is the external cause of our development. Therefore, we should link independence with opening to the outside world, adhere to long-term opening to the outside world on the basis of adhering to independence, and actively participate in economic globalization
.
Representing the fundamental interests of the overwhelming majority of the people is the most distinctive political position of Marxism. The purpose of our party is to serve the people wholeheartedly. Before the reform and opening up, the people's living standard was very low and their material interests could not be guaranteed. The implementation of reform and opening up and the liberation of the productive forces are also the manifestation of the superiority of the Communist Party and safeguard the fundamental interests of the overwhelming majority of the people, Reform and opening up are also the inevitability of representing interests. We should promote the reform of rural public health and improve the new cooperative medical system
China's nearly 30 years of historical facts eloquently show that reform and opening up is the key choice to determine the fate of contemporary China and the only way to develop socialism with Chinese characteristics and realize the great rejuvenation of the Chinese nation. This is not only a correct conclusion based on the basic principle of the universal connection of Marxist things, It is also an appropriate choice in line with China's specific national conditions. It has historical inevitability. In the current new era, only the reform and opening up that keep pace with the times is the road to China's powerful country and the rejuvenation of the Chinese nation
In order to improve the level of agricultural science and technology, China began to implement the plan of introducing international advanced agricultural science and technology, referred to as "948 plan" in August 1994, which reversed the situation of relatively backward agricultural technology and insufficient reserves in China, and optimized the agricultural industrial structure
The value of labor force refers to the value of the means of living necessary for the production, development, maintenance and continuation of labor force. Like the value of any other commodity, the value of labor force is determined by the labor time necessary for the production and reproduction of labor force, a special commodity, The production of labor force should be based on the existence of laborers, and the existence and maintenance of laborers need a certain amount of means of living
The use value of labor force is the ability to produce labor. Its use or consumption is labor, and labor condenses in goods to form value. Therefore, the characteristics of the use value of labor force goods are that it is the source of value, and it is greater than the source of labor force value, so it can produce surplus value
4 yuan = 2 yuan. Here's 0. 4 yuan, for capitalists