200 phrases are summarized in Volume 1 of junior high school, It's the new textbook of this year, with 200 phrases,

200 phrases are summarized in Volume 1 of junior high school, It's the new textbook of this year, with 200 phrases,

1. Full of Be full of 2. Listen to 3 From To from… to… Give these new books to your classmate. Put these apples into the basket

Who has taught the key sentences and phrases in unit 7 of Grade 8 English volume 1
Geese, geese, geese

1. Take off 2. Put on 3. Cut up 4. Turn on 5. Turn off 6. Mix up 7 Away Take away take away let me think let me think

Unit 10 summary of grammar, difficulties, sentences, phrases, etc,

1、 Phrases to master:
1. Play chess 2. Play the guitar 3. Speak English
Sing well the art club the swimming club
7. Join the club 8. Need help 9. Music Festival
10. Rock band 11. A little, a little 12. Email address
2、 Sentences to master:
Can you swim? Yes, a little
Can you paint? No, I can't
He can do Chinese Kung Fu
She can play the violin
What club do you want to join?
I want to join the music club
7. What can you do?
Are you good with kids?
We need some help
Can you help children with swimming?
Come and join us!
Come and show us!
Please call Zhang Heng at 622-6033
We want two good musicians for our rock band
Can you sing or dance?
I can't sing or dance
3、 Complete the sentences according to the Chinese prompts
If you want to join the chess club, you can say: I want to join the chess club
2. If you want to know if the other person can swim, you can ask: can you swim?
If you want to tell the teacher that you play the piano well, you can say: I can play the piano well
If you want to know why Tom joined the club, you can ask: why do you join the club, Tom?
5. If you want to ask if others can help you learn English, you can ask: can you help me with English?
6. If you want to know the other person's name, you can ask: May I know your name?

What is the nature of the center of gravity of a triangle

1) The center of gravity is divided into two sections with the length ratio of 2:1
2) Three middle lines divide the triangle into six small pieces, and the area of the six small pieces is equal. That is to say, the line between the center of gravity and the three vertices divides the area of the triangle into three equal parts
2) The center of gravity of a triangle with uniform material is on the geometric center of gravity. That is to say, you can pass through a line from the center of gravity and hold the line while the triangle remains horizontal

It is known that 1 of a plus 1 of B equals 9 of 2 (a + b), then B of a + B a =?

1 of a + 1 of B = 9 of 2 (a + b)
2(a+b)²=9ab
a²+b²=5ab/2
B of a + a of B
=(a²+b²)/ab
=(5ab/2)/ab
=5/2

How to learn calculus? How to reverse derivative?

Inverse derivative, that is, the solution of indefinite integral, is the inverse process of derivative
When you learn to find derivatives, you will find integrals
The main methods of indefinite integral are as follows
First exchange method
It includes explicit substitution and implicit substitution
The explicit substitution method, that is, let t =... G (x), DT =... G (x) DX, is mainly to simplify the integral formula
Implicit substitution method, that is to say, the method of approximate differentiation, uses the principle of differential to carry out implicit substitution
For example, ∫ √ (1 + x) DX = ∫ √ (1 + x) d (1 + x), we can see that DX becomes D (1 + x)
This is the differential method, D (1 + x) = (1) 'DX + (x)' DX = 0 + (1) DX = DX
The second method is to replace the element with trigonometric function to eliminate the root sign
For √ (A & # 178; - X & # 178;), 1 / √ (A & # 178; - X & # 178;), √ (A & # 178; - X & # 178;) / X and so on, let x = a * sin θ or x = a * cos θ
For √ (A & # 178; + X & # 178;), 1 / √ (A & # 178; + X & # 178;), √ (A & # 178; + X & # 178;) / X and so on, let x = a * Tan θ or x = a * cot θ
For √ (X & # 178; - A & # 178;), 1 / √ (X & # 178; - A & # 178;), √ (X & # 178; - A & # 178;) / X and so on, let x = a * sec θ or x = a * CSC θ
If there are complex trigonometric functions in the integrand, such as sin θ / (Sin & # 178; θ + cos & # 179; θ), the universal substitution u = Tan (x / 2) can be considered
But we should pay attention to the third substitution method, that is, let x = a * sec θ or x = a * CSC θ. Their inverse functions are discontinuous and need to be discussed between partitions
Integration by parts: it comes from the multiplication of derivatives
That is, the form of ∫ VDU = UV - ∫ UDV, which aims to simplify the derivative of the integrand function of the complex part
Generally, the first step is to make a differential, for example, ∫ xcosx DX = ∫ x dsinx = xsinx - ∫ SiNx DX
But some are directly used, such as ∫ LNX DX = xlnx - ∫ x D (LNX) = xlnx - ∫ DX
According to the rule against the power of three to do, that is
Inverse trigonometric functions: arcsin (x), arctan √ [x - √ (1 - X & # 178;)], arcsec (x / 2), etc
Log function: LNX, LN [x + √ (1 + X & # 178;)], log_ 7 (8x) etc
Power function: X & # 179;, x ^ (8a), x ^ (17), etc
Exponential function: e ^ (6x), a ^ (5x), etc
Trigonometric functions: SiNx, Tan (8x), sec (7x)
The inverse trigonometric function is the most complex, so do V, and the trigonometric function is the simplest, so do U
Some integrals will appear cycle phenomenon, just need to shift, for example
∫ e^x*cosx dx = ∫ e^x dsinx = e^x*sinx - ∫ sinx de^x = e^x*sinx - ∫ e^x*sinx dx
= e^x*sinx - ∫ e^x d(-cosx) = e^x*sinx + e^x*cosx - ∫ cosx de^x
=E ^ x * SiNx + e ^ x * cosx - ∫ e ^ x * cosx DX, it can be seen that ∫ e ^ x * cosx DX is repeated with the original integral, so it moves to the left of the equal sign
2 ∫ e ^ x * cosx DX = (SiNx + cosx) * e ^ x, add it to the left, and then divide both sides by constants to make the left change back to the original
∫ e ^ x * cosx DX = (1 / 2) (SiNx + cosx) * e ^ x + C, C is any constant
Rational integral method: using the principle of partial fraction and undetermined coefficient method, a large fraction is disassembled into several small fractions for simplification
For example, it is difficult to find ∫ DX / [(x + 1) (X & # 178; + 1)], so the rational integral method is adopted
Let 1 / [(x + 1) (X & # 178; + 1)] = A / (x + 1) + (BX + C) / (X & # 178; + 1), and the numerator is less than the denominator by one exponent
The right general score is 1 / [(x + 1) (X & # 178; + 1)] = [a (X & # 178; + 1) + (BX + C) (x + 1)] / [(x + 1) (X & # 178; + 1)]
The denominator is the same, just look at the numerator: 1 ≡ a (X & # 178; + 1) + (BX + C) (x + 1). This is an identity. No matter what number x is substituted into, both sides are equal
Solution 1: substituting x = - 1,1 = a (2) + 0, a = 1 / 2 is obtained
Substituting x = 0,1 = a + C = 1 / 2 + C, C = 1 / 2
Substituting x = 1,1 = (1 / 2) (2) + (B + 1 / 2) (2) = 1 + 2B + 1, we get b = - 1 / 2
That is, 1 / [(x + 1) (X & # 178; + 1)] = 1 / [2 (x + 1)] + (- x + 1) / [2 (X & # 178; + 1)]
So ∫ DX / [(x + 1) (X & # 178; + 1)] = (1 / 2) ∫ DX / (x + 1) + (1 / 2) ∫ (- x + 1) / (X & # 178; + 1) DX
Solution 2: 1 ≡ a (X & # 178; + 1) + (BX + C) (x + 1), open the brackets
1 = ax & # 178; + A + BX & # 178; + CX + BX + C, and then group the similar items
By comparing the coefficients of the two sides, we get that
A + B = 0
B + C = 0
A + C = 1
Solve the equation, a = 1 / 2, B = - 1 / 2, C = 1 / 2
So 1 / [(x + 1) (X & # 178; + 1)] = 1 / [2 (x + 1)] + (- x + 1) / [2 (X & # 178; + 1)]
There are hundreds of formulas to be used, but the above methods are enough to solve general problems
After solving the indefinite integral, remember that the constant C, which represents any constant, can only be obtained under sufficient conditions
For example, if you give a coordinate and substitute the result, you will find the value of constant C

Using the knowledge about the function of culture, this paper analyzes the theoretical basis of our party's important decision of "building a socialist cultural power"
Cultural knowledge

】(1) Culture is the blood of a nation and the spiritual home of the people, representing the civilization and development level of a country and a nation. As a spiritual force, culture can be transformed into material force in the process of people's understanding and transforming the world, which has a profound impact on social development. On the other hand, culture is created by people, which in turn affects everyone, Culture influences people's communication behavior, communication mode, practice activity, cognition activity and thinking mode. Culture can also shape life, At present, some institutional and policy factors that restrict and restrict the development of cultural industry have not been solved. The role of culture in leading fashion, educating the masses, serving the society and promoting development has not been fully played. From this point of view, we must also vigorously develop cultural industry
(2) Today's world is in a period of great development, great change and great adjustment. Culture has increasingly become an important source of national cohesion and creativity, an important factor in the competition of comprehensive national strength, and an important support for economic and social development, It is an inevitable choice for China to move from a big economic country to a powerful economic country and for the rejuvenation of the Chinese nation
(3) Our country is in and will be in the primary stage of socialism for a long time. The main contradiction of our country is still the contradiction between the people's growing material and cultural needs and the backward social production. Vigorously developing advanced culture is the inevitable requirement to solve the main contradiction of our country
(4) Although China is a big country of cultural resources and cultural industry, it is not a cultural power, which is not commensurate with the status of the second largest economic entity in the world. Especially in today's world, western culture is still in the mainstream position. China is still facing ten severe challenges in the field of culture, so as to enhance the national cultural soft power

Find the differential of the function determined by e ^ y = (x + y) ^ 1 / 2

The two sides are the same
d(e^y)=d[(x+y)^1/2]
e^ydy=d(x+y)/[2(x+y)^1/2]
e^ydy=(dx+dy)/2(x+y)^1/2
2e^y(x+y)^(1/2)dy=dx+dy
dy/dx=1/[2e^y(x+y)^(1/2)-1]
We can also use the partial derivative formula of implicit function
dy/dx=-Fx/Fy；
above!
luck!

Given α, β ∈ (0, π), Tan (α / 2) = 0.5, sin (α - β) = 5 / 13, find the value of cos β

Because α ∈ (0, π), so α / 2 ∈ (0, π / 2), so sin α = 2Sin α / 2cos α / 2 = (2Sin α / 2cos α / 2) / (sin ^ 2 α / 2 + cos ^ 2 α / 2) = (2tan α / 2) / (Tan ^ 2 α / 2 + 1) = 1 / (1 / 4 + 1) = 4 / 5 > 0 cos α = (COS ^ 2 α / 2-sin ^ 2 α / 2) / (sin ^ 2 α / 2 + cos ^ 2 α / 2) = (1 -

A study on the problem of off form calculation with answers in grade five
Summer homework, not too difficult, not too easy

75÷〔138÷（100-54）〕 85×(95－1440÷24)
80400－(4300＋870÷15) 240×78÷（154-115）
1437×27＋27×563 〔75-（12+18）〕÷15
2160÷〔（83-79）×18〕 280＋840÷24×5
325÷13×(266－250) 85×(95－1440÷24)
58870÷(105＋20×2