Đáp án + Giải thích các bước giải:
$x^{2}y+y^2x+x^2z+z^2x+y^2z+z^2y+2xyz$
$=(x^2y+z^2y+2xyz)+(y^2x+y^2z)+(z^2x+x^2z){}$
$=y(x+z)^2+y^2(x+z)+xz(x+z){}$
$=(xy+yz)(x+z)+(x+z)(y^2+xz)^{}$
$=(x+z)(xy+yz+y^2+xz)^{}$
$=(x+z)[x(y+z)+y(y+z)]$
$=(x+z)(x+y)(y+z)^{}$
Đáp án:
`x^2y+xy^2+x^2z+xz^2+y^2z+yz^2+2xyz`
`= (x^2y+xy^2)+(x^2z+xyz)+(yz^2+xz^2)+(y^2z+xyz)`
`= xy(x+y)+xz(x+y)+z^2(x+y)+yz(x+y)`
`= (x+y)(xy+xz+z^2+yz)`
`= (x+y)[(xy+xz)+(z^2+yz)]`
`= (x+y)[x(y+z)+z(y+z)]`
`= (x+y)(y+z)(x+z)`
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giúp với ạ Bài 14: Khoanh tròng vào đáp án đúng: Benefit of living in the countryside. While many people prefer city life, a lot of people want to send their life in a rural area. The countryside are often(1) _________than the city because there are not as many factories and traffic as in big cities. The country folk can be (2) _________and they often live(3) _________than city dwellers. Besides, life in the countryside is(4) _________and peaceful because the crime rate is much(5) _________. The rural areas are(6) _________populated than the urban area but the neighbors are(7) _________and more helpful. Life in the countryside is(8) _________for old people than the energetic youngsters. 1.A.less polluted B.more polluted C.less pollutedly D.more pollutedly 2.A.more healthy B.healthier C.more healthily D.helthily. 3.A.longly B.longer C.shortly D.shorter 4.A.more simple B.simpler C.simply D.more simply 5.A.higher B.highly C.lower D.lowly 6.A.more densely B.more dense C.less D.less dense 7.A.more friendly B.friendlier C.friendly D.less friendly 8.A.more suitable B.more suitbly C.less suitably D.suitably.
tìm 4 số nguyên dương liên tiếp biết tích của chúng là 120
Phân tích các đa thức sau thành nhân tử : 1. 25x² - 10xy + y² 3. 4y² + 4y +1 4. 81x² - 64y² 5. (x-1)² - (x+1)²
giúp với ạ:< Bài 13; Viết lại câu bằng từ đã cho sao cho nghĩa câu không thay đổi theo mẫu: 0.This exercise is easier than that one. → That exercise is more difficult than that one. 1.Mr Smith is wealthier than Mr.Brown. → Mr Brown___________________________________ 2.My house is smaller than my parent’s house. → My parent’s house____________________________ 3.The black dress is more expensive than the red one. → The red dress _____________________________ 4.→ Yesterday______________________________ 5.I don’t think you are taller than me. → I don’t think I_________________________________ 6.Is Jim worse at Math than John? → Is John______________________________________ 7. Jim looks much younger than his classmates. → Jim’s classmates____________________________ 8.Your hair is longer than mine. → My hair_________________________
II. Read the passage carefully and choose the correct answer to each question. A good deal of fascinating research has been done about the reading patterns of young people, and it is surprising to discover at what an early age children start expressing preferences for particular kinds of books. A recent report, which examined in detail the reading habits of primary-school children, showed that even seven-year-old boys and girls have clear views about what they want to read. Girls, in general, read more, and far more girls than boys preferred reading stories. Boys were showing a taste for the more instant appeal of picture stories, or else books about their hobbies. These tastes continue unchanged until the children are teenagers. Apparently girls read more in general, but more fiction in particular. You could say that there are more opportunities for girls to read fiction: magazines encourage the fiction habit in girls in their early teens, and by their late teens, girls have probably moved on to the adult women’s magazines. Teenage boys tend to buy magazines about their hobbies: sports, motorcycles, heavy transport and so on. 36. Recent research into children’s reading has shown that they ………………….. A. start to read at a very early age B. have formed their reading tastes by the time they are seven C. examine in detail what they read at school D. can read clearly and distinctly in primary school 37. A close look at the reading habits of boys and girls shows that …………………. A. schools give more encouragement to girls than to boys B. magazines appeal more to boys than girls C. Picture stories appeal more to girls than boys D. Girls are more interested in fiction than boys 38. According to the passage………………... A. far more boys than girls are interested in love stories B. There are more opportunities for girls to buy magazines than for boys C. Children generally don’t care what they should read D. Teenage boys show a taste for magazines about their hobbies 39. The word ‘fascinating’ means most nearly the same as …………… . A. having a lot of action B. having a lot of information C. having great attraction D. having great pleasure 40. Which of the following is NOT true? A. Girls start reading earlier than boys. B. Girls read more than boys when they are teenagers. C. Girls prefer reading fiction when they are teenagers. D. Girls are usually interested in women’s magazines in their late teens. D. WRITING I. Complete the second sentence so that it has a similar meaning to the first one. 41. I’m sorry I didn’t come to your birthday party last night. If only ………………………………………………………………………... 42. Lisa has been always mean with money, so she doesn’t have many friends. If Lisa ………………………………………………………………………............. 43. People say that the telephone was invented by Graham Bell. The telephone …………………………………………………………………………….. 44. You may be very intelligent, but you should be careful about this. No matter ……………………………………………………………………….. 45. “Why don’t you write to your parents, John?” said Peter Peter suggested ……………………………………………………………… trả lời hộ mik với ạ
giúp em với:<< Bài 12; Gạch chân lỗi sai trong mỗi câu sau và sửa lại cho đúng: 1.Their life has been more comfortably since they moved to the city. 2.She looks more pretty in this white dress. 3.The manager wants us to work more hardly. 4.This week you looks more healthily than last week. 5.Everyone in my town is looking for more better crop this year. 6.Jim runs more fastly than his friends. 7.I think a settle life is more better than a nomadic life. 8.Today Jim performs less confident than usual. 9.The heavy rain makes it more difficultly to drive. 10.Their team preformed much more well than our team.
Cho mẩu kim loại Na có khối lượng m gam tan hoàn toàn trong lọ đựng 174 ml dung dịch HCl 10% (khối lượng riêng là 1.05g/ml)a, Viết phương trình hóa học có thể xảy ra.b, Với giá trị như thế nào của m, dung dịch thu được có :- Tính axit ?- Tính bazo ?
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