The school bought 135 new books of three kinds, among which children's books are three times of popular science books, and story books are 12 times of popular science books?

The school bought 135 new books of three kinds, among which children's books are three times of popular science books, and story books are 12 times of popular science books?

Answer: there are 90 children's books, 30 popular science books and 15 story books

The school bought 135 new books of three kinds, among which children's books are three times of popular science books, and story books are 12 times of popular science books?

Answer: there are 90 children's books, 30 popular science books and 15 story books

The main diagonal of n-order determinant is x, others are a,

Add all the lines to the first line, and the first line becomes x + (n-1) A. put forward the common factor, the first line becomes 1, the other lines subtract a times of the first line, and then it becomes the upper triangular determinant, and the final result is [x + (n-1) a] * (x-a) ^ (n-1)

The third problem is the last problem of factoring
4-12(x-y)+9(x-y)²
It's factorization, not computation
Wrong, it should be 4 + not 4-
4+12(x-y)+9(x-y)²

4+12(x-y)+9(x-y)²
=（3x-3y+2)²

Here is a set of numbers arranged in the shape of a tower:
First line 1
Second line - 1 / 2 1 / 3
The third line - 1 / 4 1 / 5 - 1 / 6
The fourth line - 1 / 7 1 / 8 - 1 / 9 1 / 10
The fifth line - 1 / 11 1 / 12 - 1 / 13 1 / 14 - 1 / 15
…… …… ……
Q: what is the eighth number in line 199? - what is the eighth number in line 1 / 2008?

Sum 1-198 and add 8
=19709
8 is even, which is positive,
So the eighth number in line 199 is 1 / 19709
There are 62 rows in total (1 + 62) * 62 / 2 = 1953
-1 / 2008 in line 63 number 55

What is the product of all negative integers whose absolute value is less than 6?
It's not just numbers, it's numbers

-1,-2,-3,-4,-5
(-1)*(-2)*(-3)*(-4)*(-5)=-120

A summary of all the knowledge of English in volume one of junior high school
The more complete the better

First volume of junior high school English all knowledge and practice:
[knowledge sorting]
1. Key phrases
1. Sit down
2. on duty
3. in English
4. have a seat
5. at home
6. look like
7. look at
8. have a look
9. come on
10. at work
11. at school
12. put on
13. look after
14. get up
15. go shopping
2. Important sentence patterns
1. help sb. do sth.
2. What about… ?
3. Let’s do sth.
4. It’s time to do sth.
5. It’s time for …
6. What’s… ? It is… / It’s…
7. Where is… ? It’s… .
8. How old are you? I’m… .
9. What class are you in? I’m in… .
10. Welcome to… .
11. What’s … plus… ? It’s… .
12. I think…
13. Who’s this? This is… .
14. What can you see? I can see… .
15. There is (are) … .
16. What colour is it (are they)? It’s (They’re)…
17. Whose … is this? It’s… .
18. What time is it? It’s… .
3. Communicative language
1. Good morning, Miss/Mr… .
2. Hello! Hi!
3. Nice to meet you. Nice to meet you, too.
4. How are you? I’m fine, thank you/thanks. And you?
5. See you. See you later.
6. Thank you! You’re welcome.
7. Goodbye! Bye!
8. What’s your name? My name is … .
9. Here you are. This way, please.
10. Who’s on duty today?
11. Let’s do.
12. Let me see.
4. Important grammar
1. The usage of verb be;
2. The usage of personal pronouns and possessive pronouns;
3. The usage of singular and plural nouns and possessive cases;
4. The basic usage of articles;
5. The usage of there be sentence pattern
[famous teacher's explanation]
1. in/on
When representing the spatial position, in means to be within the scope of a certain space, on means to be above the surface of an object
There is a bird in the tree
There is a picture on the wall
2. this/that/these/those
(1) This is often used to refer to people and things closer to the speaker in time and place. These are plural forms of this. That is often used to refer to people and things farther away from the speaker in time and place
You look in this box and I'll look in that one over there
I want this car, not that car
Take these books to his room, please
This is mine; that's yours
These are apples; those are oranges
(2) This often refers to me and that often refers to the other party
This is Mary speaking. Who's that?
3. There be/ have
"There be" means "there is someone or something somewhere or at some time". Its structure is: there be + someone or something + adverbial of place or time. The noun after "there be" is actually the subject. The form of the verb "be" should be consistent with the subject in number. The noun after "be" is used when it is singular or uncountable, and is used when it is plural
(1) There is a big bottle of coke on the table
(2) There is a doll in the box
(3) There are many apples on the tree
In a word, there be structure emphasizes a kind of objective existence "you". Have means "have, possess, have", that is, sb. Have / has sth.. The subject is generally a noun or pronoun, which belongs to the subject
(4) I have two brothers and one sister
(5) That house has four rooms
4. look/ see/ watch
(1) "Look" means "look" and "look" refers to the action of looking seriously and emphatically. It means that you pay attention to looking consciously, but you don't have to see it, so as to remind the other party to pay attention
Look! The children are playing computer games
Look! What's that over there?
When used alone, it is an intransitive verb, such as emphasizing to see someone / thing, followed by the preposition at
He's looking at me
(2) See is a transitive verb that can be followed by an object
What can you see in the picture?
Look at the blackboard. What did you see on it?
(3) Watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch, watch
Yesterday we watched a football match on TV
4. put on/ / in
Put on, put on, put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on put on
"In" is a preposition, which means "dressed" stressed state. It can be used as attributive, slogan and adverbial
It's cold outside, put on your coat
He puts on his hat and goes out
The woman in a white shirt is John's mother
5. house/ home/family
House: "house" refers to the building where one lives; home: "home" refers to the place where one often lives with his family; family: "family", "family member"
Please come to my house this afternoon
He is not at home
My family all get up early
6. fine, nice, good, well
All of them can be used as adjectives to express "good", but the first three can be used as both predicative and attributive, while the latter can only be used as predicative
(1) "Fine" refers to "fine" in quality, and "good health" refers to "good health"
It can be used to mean "sunny day"
Your parents are very fine
That's a fine machine
It's a fine day for a walk today
(2) Nice mainly focuses on the appearance of people or things. It means "beautiful" and "beautiful". It can also be used to greet or praise others
Lucy looks nice
Those dresses are very nice
Nice to meet you
It's very nice of you
(3) Good refers to "good moral character" when it comes to people and "good quality" when it comes to things
Her son is a good student
The red car is very good
(4) Well can only be used to describe a person's "good health", but it can't be used as an attributive. It can also be used as an adverb as an adverbial
I'm very well, thanks
My friends sing well
[examination site scanning]
In this unit, the test points of senior high school entrance examination mainly focus on:
1. The usage of verb be;
2. The usage of personal pronouns and possessive pronouns;
3. The usage of singular and plural nouns and possessive cases;
4. The basic usage of articles;
5. The usage of there be sentence pattern
6. Vocabulary, phrases and sentence patterns learned in this unit;
7. Daily communication language learned in this unit
The form of examination can be single item, cloze, essay and complete sentence
[example of high school entrance examination]
1. (2004 Beijing high school entrance examination questions)
Mary, please show ________ your picture.
A. my B. mine C. I D. me
In this question, the verb show is followed by a double object, and the blank space should be filled with the object me of the personal pronoun as the object
2. (questions of senior high school entrance examination in Xuhui District of Shanghai in 2004)
_________ orange on the desk is for you, Mike.
A. A B.An C. / D. The
Answer: D. this question examines the basic usage of the article. Because it refers to the orange on the desk, it uses the definite article the
3. (2004 Harbin high school entrance examination questions)
---What _______ the number of the girls in your class?
---About twenty.
A. is B. am C. are D. be
The number as the subject should be the singular third person, and the verb be becomes is
4. (questions of senior high school entrance examination in Shaanxi Province in 2004)
There _______ a football match on TV this evening.
A. will have B. is going to be C. has D. is going to have
B. there be There is a difference between the sentence pattern and the verb have. The sentence pattern itself means "there is someone or something in a certain place", which can not be mixed with the verb have
[full mark drill]
1、 Fill in the blanks
1. ---What colour is the bike?
---It’s _______ orange.
A. an B. a C. / D. the
2. That isn’t her bag. It’s ________ .
A. my B. I C. mine D. me
3. ---Oh, your kite is very nice.
---__________________ .
A. That’s right B. No, it’s not nice C. Yes, it is D. Thank you
4. The woman is sixty, but she _______ young.
A. is B. sees C. looks D. watches
5. It’s time ________ lun