If "△" is a new operation symbol, let x △ y = XY + X + y, then in 2 △ M = - 16, the value of M is______ ．

If "△" is a new operation symbol, let x △ y = XY + X + y, then in 2 △ M = - 16, the value of M is______ ．

According to the meaning of the question: 2 △ M = 2m + 2 + M = - 16, sort out: 3M = - 18, solution: M = - 6

If "△" is a new operation symbol, let x △ y = XY + X + y, then in 2 △ M = - 16, the value of M is ()
A. 8B. -8C. 6D. -6

According to the new definition: 2 △ M = 2m + 2 + M = - 16, transfer and merge: 3M = - 18, solution: M = - 6

It's a cuboid glass container that is 40 cm long, 20 cm wide and 50 cm deep. If 30 liters of water is injected into the container, what's the depth of water?
Thickness ignored

30 L = 30000 ml = 30000 CC
40 × 20 = 800 square centimeter
Height (depth) = 30000 cm3 ／ 800 cm2 = 37.5 cm

If S3 = 7 and S6 = 63, then q can be ()
A. 2B. -2C. 3D. -3

∵ {an} is an equal ratio sequence, let the first term be a, the common ratio be q, ∵ S3 = a (1 − Q3) 1 − Q, S6 = a (1 − Q6) 1 − Q, S3 = 7, S6 = 63, ∵ s6s3 = 1 − q61 − Q3 = 1 + Q3 = 637 = 9, namely Q3 = 8, the solution is: q = 2

If the length or width of a rectangular test field increases by 8 meters or 6 meters, the area will increase by 72 square meters

Let length x width y
Then: (x + 8) * Y-X * y = 72, y = 9
x*(y+6)-x*y=72 x=12
Conclusion: area = x * y = 12 * 9 = 108 square meters

How to use various punctuation marks

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Basic rules
3.1 punctuation marks are used to assist writing to record language. They are an organic part of written language and are used to express pause, mood and the nature and function of words. 3.2 there are 10 kinds of punctuation marks commonly used, including punctuation marks and punctuation marks. The function of punctuation marks is to punctuate, mainly to express pause and mood when speaking. Punctuation marks are also divided into sentence end punctuation marks and sentence end punctuation marks, There are three kinds of punctuation marks: full stop, question mark and exclamation mark, which indicate the pause at the end of a sentence and the mood of the sentence. Punctuation marks are used in a sentence, including comma, dun sign, semicolon and colon, which indicate various kinds of pause in a sentence. The function of punctuation marks is to indicate the nature and function of a sentence. There are nine commonly used punctuation marks, That is: quotation marks, brackets, dashes, ellipsis, emphasis, connection number, interval number, book name number and proper name number!
Full stop
4.1.1 the form of a full stop is ".". There is another form of a full stop, that is, a dot ".", which is generally used in scientific and technological literature. 4.1.2 the pause at the end of the declarative sentence is a full stop. For example: a) Beijing is the capital of the people's Republic of China. B) modesty makes people progress and pride makes people fall behind. C) Asia is a vast region, spanning the cold, warm and hot zones, Because of the different terrain and distance from the sea, the climate is complex and varied
question mark
4.2.1 the form of the question mark is "?". 4.2.2 the pause at the end of the question is a question. For example: a) have you seen the golden monkey? B) what's his name? C) go or not? 4.2.3 the end of the rhetorical question is also a question mark. For example: a) don't you know me? B) how can you say that?
exclamation mark
4.3.1 the form of exclamation mark is "!". 4.3.2 the pause at the end of exclamation sentence, use exclamation mark. For example: a) strive for the prosperity of the motherland! B) how I want to see him! 4.3.3 at the end of strong imperative sentence, also use exclamation mark. For example: a) you go out! B) stop shooting! 4.3.4 at the end of strong rhetorical question, Where can I compare with him!
comma
4.4.1 the form of a comma is "," 4.4.2 if there is a pause between the subject and predicate in the sentence, use a comma. For example, most of the stars we can see are stars. 4.4.3 if there is a pause between the verb and the object in the sentence, use a comma. For example, it should be noted that science requires a person to contribute his whole life It is said that there are more than 100 gardens in Suzhou, but I have been to no more than 10
Dunhao
4.5.1 the Dun sign is in the form of ",". 4.5.2 the pause between the coordinate words in the sentence, use the Dun sign. For example: a) the Amazon River, the Nile River, the Mississippi River and the Yangtze River are the four major rivers in the world. B) a square is a quadrilateral with equal four sides and right angles
semicolon
4.6.1 the form of semicolon is ";". 4.6.2 the pause between parallel clauses in complex sentences is semicolon. For example: a) language is used to express feelings; words are used to record words and events. B) in the upper reaches of the Yangtze River, Qutang gorge is like a gate and a dangerous Gorge; Wuxia gorge is like a winding Gallery, and every turn is like a wonderful landscape painting, The water in Xiling Gorge is dangerous, with rapids and shoals everywhere. 4.6.3 a semicolon is also used between the front and back parts of the first level of the multiple repetitions of non parallel relations (such as turning relations, causality, etc.), They have the right to vote and stand for election regardless of nationality, race, sex, occupation, family background, religious belief, education level, property status, length of residence, etc., except those who are deprived of political rights according to law, For example, the administrative divisions of the people's Republic of China are as follows: (1) the whole country is divided into provinces, autonomous regions and municipalities directly under the central government; (2) provinces and autonomous regions are divided into autonomous prefectures, counties, autonomous counties and cities; (3) counties and autonomous counties are townships, nationality townships and towns
colon
4.7.1 the colon is in the form of ":". 4.7.2 after the address, it means to bring up the following. For example: comrades, friends, it's time for the meeting. 4.7.3 after "say, think, yes, prove, announce, point out, disclose, for example, as follows", it means to bring up the following. For example: he was very surprised to say: "ah, So it's you! "4.7.4 is used after the general discourse, which means to cause the following part. For example, there are four gates in Beijing Forbidden City: Meridian Gate, Shenwu gate, Donghua gate and Xihua gate. 4.7.5 is used after the words that need to be explained, which means to lead to explanation or explanation. For example, the date of foreign language book fair: October 20 to November 10 time: 8 am to 4 pm Venue: No.16 Gongti East Road, Chaoyang District, Beijing organizer: China National Book Import and Export Corporation 4.7.6 colon can also be used to summarize the above. For example: Zhang Hua was admitted to Peking University and studied in the Department of chemistry; Li Ping entered secondary technical school and majored in mechanical manufacturing; I worked as a salesman in a department store: we all have a bright future
Quotation marks
4.8.1 quotation marks are in the form of "double quotation marks" and "single quotation marks". 4.8.2 quotation marks are used to mark the words directly quoted in the text. For example: a) Einstein said: "imagination is more important than knowledge, because knowledge is limited, and imagination surveys everything in the world, promotes progress, and is the source of knowledge evolution." B) "man catches losses, The maxim of "modesty benefits" has been around for at least two thousand years. C) the horse in Xu Beihong's works, as some critics put it, "has both spirit and form, and is full of vitality". 4.8.3 the objects that need to be discussed should be marked with quotation marks. For example, the ancients had a basic requirement for writing articles, which was called "having things in order", 4.8.4 words with special meaning are also marked with quotation marks. For example: a) looking up from the foot of the mountain, you can see that the torches are arranged in many zigzag shapes, which are connected to the sky and connected with the starlight. You can't tell whether they are torches or stars. B) it's better to have fewer such "intelligent people". 4.8.5 when quotation marks are used inside, double quotation marks should be used outside, He stood up and asked, "teacher, what do you mean by" orderly "
brackets
4.9.1 the usual form of brackets is "()". In addition, there are square brackets "[]", hexagonal brackets "{}" and square head brackets "[]". 4.9.2 the explanatory words in the text are marked with brackets. If you annotate a certain word in a sentence, the parenthesis is next to the annotated word; if you annotate the whole sentence, the, A) the discovery of the Chinese ape man in China is a great contribution to the Anthropology of the ancients. B) writing research articles is different from literary creation, so we can't spread out the paper to "improvise" (in fact, literary creation also needs to have literacy to have "improvisation")
Dash
4.10.1 the form of dash is "-". 4.10.2 the explanation in the text is marked with dash. For example: a) step into the golden gate, pass through the wide air door hall and cloakroom, and then come to the central hall, the hub of the great hall building. B) for the happiness of the people of the whole country, including ourselves, each of us should work hard, Work hard. 4.10.3 the topic changes suddenly and is marked with a dash. For example, "it's hot today - when are you going to Shanghai?" Zhang Qiang told Xiao Wang who just came in. 4.10.4 the voice is prolonged, like a dash after the voice words. For example, "Wu -" the train is starting. 4.10.5 list the items and use a dash before them, Environmental physics is divided into the following five branches: Environmental Acoustics; Environmental Optics; environmental heat; environmental electromagnetism; environmental aerodynamics; environmental physics;
ellipsis
4.11.1 the ellipsis is in the form of ".", six small dots, occupying the position of two words. If it is the omission of the whole passage or poem line, it can be expressed by twelve small dots. 4.11.2 the ellipsis of quotation is indicated by ellipsis. For example, she hummed the lullaby gently: "the moon is bright, the wind is quiet, and the leaves cover the window lattice.", In the flower market of Guangzhou, peony, bell, Narcissus, plum blossom, chrysanthemum, camellia, and Magnolia are all crowded together in spring and autumn. 4.11.4 the words are intermittent, which can be marked with an ellipsis. For example: "I'm sorry. Everyone, I didn't. finish the task."
mark of emphasis
4.12.1 the form of emphasis is ".". 4.12.2 the words, words and sentences that require special attention of the readers should be marked with emphasis. For example, business is done, not blown out
hyphen
4.13.1 the form of connection number is "-", occupying the position of one word. There are three other forms of connection number, namely long horizontal "-" (occupying the length of two words), half character line "-" (occupying the length of half a word) and wave pattern "~" (occupying the length of one word). 4.13.2 two related nouns form a meaning unit, For example: a) the area north of Qinling Huaihe River belongs to temperate monsoon climate zone, with high temperature and rainy in summer and cold and dry in winter. B) compound sodium chloride injection, also known as any ringer lock solution, is used for medical and mammalian physiological experiments, Lu Xun (1881-1936)