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8 tháng 4 2020

a/ \(\left(x-1\right)^2=x^2-2x+1\) nên chọn đáp án D

b/ \(\left(x+2\right)^2=x^2+4x+4\) nên chọn đáp án C

c/ \(\left(a-b\right)\left(b-a\right)=-\left(a-b\right)\left(a-b\right)=-\left(a-b\right)^2\) nên chọn đáp án A

d/ \(-x^2+6x-9=-\left(x^2-6x+9\right)=-\left(x-3\right)^2\) nên chọn đáp án D

Exercise 4: Chän tõ ®óng trong sè c¸c tõ ®· cho :1. This car is ............. as  expensive as our car.    a. double                              b. twice                                    c. much                                    d. a lot2. The harder she works, the ........ money she earns.    a. better                                b. much                                   c. more                         d. less3. The .......  you are, the ............ it is to concentrate.    a. more...
Đọc tiếp

Exercise 4: Chän tõ ®óng trong sè c¸c tõ ®· cho :

1. This car is ............. as  expensive as our car.

    a. double                              b. twice                                    c. much                                    d. a lot

2. The harder she works, the ........ money she earns.

    a. better                                b. much                                   c. more                         d. less

3. The .......  you are, the ............ it is to concentrate.

    a. more tired / more hard     b. more tired/ harder                c. tired / hard               d. tired / hardly

4. The ...... she waited, the ........... she became.

    a. more long / more impatient                                               b. longer / impatient  

    c. long / more impatient                                                        d. longer / more impatient

5. The standard of living in Canada is higher  ............. in many countries.

    a. than that                           b. as that                                  c. than those                 d. as those

6. My boss is very young. He's ............ than I am.

    a. younger 10 years             b. 10 years more young           c. 10 years younger    d. 10 years young

7. Life in Hai Phong is ........ expensive than that in Hai Duong.

    a. a little more                      b. a little much                         c. far much                  d. more a lot

8. What do you think about the parks in London ? Are they bigger ............... in Ha Noi ?

    a. than that                           b. than those                            c. as that                      d. as those

9. ................. pollution is being produced nowadays.

    a. Much and much               b. Many and many       c. Better and better       d. More and more

10. The ........... you spend learning, ........... your study result will be.

    a. much time / the best   b. more time / the good  c. more time /  the better   d. better time / the well

11. Is your weight ................... Hoa's.

    a. the same as                      b. as the same                          c. the same like            d. like the same

12. His car is ................ of the two cars.

    a. more expensive                b. the more expensive              c. expensive         d. the most expensive

13. He’s one of the richest man in our country. He lives ............ the King!

    a. like                                   b. as                                         c. alike                         d. unlike

14. - I’ve had  enough for lunch. I can’t eat ................

    a. any more                          b. no more                                c. more any                  d. any much

1
10 tháng 11 2021

1. This car is ............. as  expensive as our car.

    a. double                              b. twice                                    c. much                                    d. a lot

2. The harder she works, the ........ money she earns.

    a. better                                b. much                                   c. more                         d. less

3. The .......  you are, the ............ it is to concentrate.

    a. more tired / more hard     b. more tired/ harder                c. tired / hard               d. tired / hardly

4. The ...... she waited, the ........... she became.

    a. more long / more impatient                                               b. longer / impatient  

    c. long / more impatient                                                        d. longer / more impatient

5. The standard of living in Canada is higher  ............. in many countries.

    a. than that                           b. as that                                  c. than those                 d. as those

6. My boss is very young. He's ............ than I am.

    a. younger 10 years             b. 10 years more young           c. 10 years younger    d. 10 years young

7. Life in Hai Phong is ........ expensive than that in Hai Duong.

    a. a little more                      b. a little much                         c. far much                  d. more a lot

8. What do you think about the parks in London ? Are they bigger ............... in Ha Noi ?

    a. than that                           b. than those                            c. as that                      d. as those

9. ................. pollution is being produced nowadays.

    a. Much and much               b. Many and many       c. Better and better       d. More and more

10. The ........... you spend learning, ........... your study result will be.

    a. much time / the best   b. more time / the good  c. more time /  the better   d. better time / the well

11. Is your weight ................... Hoa's.

    a. the same as                      b. as the same                          c. the same like            d. like the same

12. His car is ................ of the two cars.

    a. more expensive                b. the more expensive              c. expensive         d. the most expensive

13. He’s one of the richest man in our country. He lives ............ the King!

    a. like                                   b. as                                         c. alike                         d. unlike

14. - I’ve had  enough for lunch. I can’t eat ................

    a. any more                          b. no more                                c. more any                  d. any much

V. Chän ®¸p ¸n ®óng nhÊt trong c¸c ®¸p ¸n A, B, C, hoÆc D. 1. My father is ........ man.          A. a old                         B. an old                        C. not young                   D. not very young2. What was the matter with him? He …….. a toothache  A.  to have                  B. have                            C. has                    D. had3. Do you have any toothpaste? I’d like a large ...................   A. tin                                B....
Đọc tiếp

V. Chän ®¸p ¸n ®óng nhÊt trong c¸c ®¸p ¸n A, B, C, hoÆc D.

1. My father is ........ man.      

   A. a old                         B. an old                        C. not young                   D. not very young

2. What was the matter with him? He …….. a toothache 

A.  to have                  B. have                            C. has                    D. had

3. Do you have any toothpaste? I’d like a large ...................

   A. tin                                B. roll                              C. bar                          D. tube

4. What .....  does Peter study at school? - He has Maths, English, Art….

A. objects               B. subjects              C. food                    D. drink

5. Bangkok is ............. capital of Thailand.  

   A. a                 B. one       C. X                   D. the

6. There are ................. girls in his class.

   A. not        B. no               C. none                      D. any

7. ......... she plays the piano!

   A. How beautiful           B. How beautifully    C. What good               D. What well

8. On .... we often go out. 

   A. nights of Saturday    B. Saturday nights          C. Saturday’s nights              D. none is correct

9. I don’t want much sugar in coffee. Just ........., please. 

   A. little                             B. a little    C. few                   D. a few

10. The weather is ..................... today than yesterday.

   A. much better          B. very better     C. too better          D. so better

11. A. Always they do their homework.        B. They always do their homework.

      C. They do their homework always.      D. They always do their homeworks.

12. Why do you like Music? Because I like …..

A. to read                 B. to draw                        C. to write              D. to sing

13. It’s very hot. Why ...... go swimming? 

   A. not we                   B. not                              C. don’t we      D. Both B & C are correct

14. At an intersection, you ....... slow down. 

   A. can     B. should          C. must                      D. have

15. Which word has the final sound /s/: 

   A. bananas B. carrots        C. apples                        D. guavas

16. Don’t move. You have a .............. leg. 

   A. break   B. breaking     C. broke                         D. broken

17. If there aren’t any trash cans, we should put it in a bag and ..................... .

   A. take it to our home      B. take it to home       C. take it home        D. take it back our house

18. Make sure ........... is no traffic.

   A. they    B. it                                              C. there                            D. some

19. Let’s eat here. The ............. seems very good. 

   A. list                        B. paper    C. programme                       D. menu

20. Don’t ..................... electricity. 

   A. save    B. waste        C. use                             D. leave

2
28 tháng 11 2023

1. B. an old
2. D. had
3. D. tube
4. B. subjects
5. A. a
6. C. none
7. B. How beautifully
8. B. Saturday nights
9. B. a little
10. A. much better
11. B. They always do their homework.
12. D. to sing
13. C. don’t we
14. B. should
15. C. apples
16. D. broken
17. C. take it home
18. C. there
19. D. menu
20. B. waste

28 tháng 11 2023

cảm ơn nha

haha

1 tháng 6 2021

a,x2-y2-2x+2y
= (x+y)(x-y) - 2(x-y)
= (x-y)(x+y-2)
b,2x+2y-x2-xy
= 2(x+y) - x(x+y)
= (x+y)(2-x)
c,3a2-6ab+3b2-12c2
= 3(a2 - 2ab + b2 - 4c2)
= 3[(a-b)2 - 4c2)
= 3(a-b-2c)(a-b+2c)
d,x2-25+y2+2xy
= (x+y)2 - 25
= (x+y+5)(x+y-5)

e) a2+2ab+b2-ac-bc

= (a+b)2-c(a+b)

= (a+b)( a+b-c)

f) x2-2x-4x2-4y

= -3x2-2x-4y

= -(3x2+2x+4y)

g)x2y-x3-9y+9x

= x2(y-x)-9(y-x)

= (y-x)(x2-9)

h) x2(x-1)+16(1-x)

= x2(x-1)-16(x-1)

= (x-1)(x2-16)

= (x-1)(x-4)(x+4)

n) 81x2-6yz-9y2-z2

= (9x)2-[(3y)2+6yz+z2]

=(9x)2-(3y+z)2

=(9x+3y+z)(9x-3y-z)

m) xz- yz-x2+2xy-y2

= z(x-y)-(x2-2xy+y2)

= z(x-y)-(x-y)2

= (x-y)(z-x+y)

 p) x2 + 8x + 15

= x2 + 3x + 5x + 15

= x(x+3) + 5(x+3)

= (x+3)(x+5)

k) x2 - x - 12

= x2 + 3x - 4x - 12

= x(x+3) - 4(x+3)

= (x+3)(x-4)

20 tháng 12 2018

Chọn C

26 tháng 3 2019

Chọn A.

(1) (X) FeCO3 + HCl ® (X1) FeCl2 + (X2) CO2 + H2O                  

(2) (X1) FeCl2 + NaOH ® (X3)¯ Fe(OH)2 + (X4) NaCl

(3) (X1) FeCl2 + Cl2 ® (X5) FeCl3                                                  

(4) (X3) Fe(OH)2 + H2O + O2 ® (X6)¯ Fe(OH)3                            

(5) (X2) CO2 + Ba(OH)2 ® (X7) Ba(HCO3)2                                  

(6) (X7) Ba(HCO3)2 + NaOH ® (X8) ¯ BaCO3 + (X9) Na2CO3 + …

(7) (X8) BaCO3 + HCl ® (X2) CO2 +…      

(8) (X5) FeCl+ (X9) Na2CO3 + H2O ® (X4)  NaCl …                  

Tất cả các ý trên đều đúng

Cho các sơ đồ phản ứng: (1) (X) + HCl ® (X1) + (X2) + H2O               (2) (X1) + NaOH ® (X3)¯ + (X4) (3) (X1) + Cl2 ® (X5)                                      (4) (X3) + H2O + O2 ® (X6)¯                          (5) (X2) + Ba(OH)2 ® (X7)                             (6) (X7) + NaOH ® (X8) ¯ + (X9) + … (7) (X8) + HCl ® (X2) +…                             (8) (X5) + (X9) + H2O ® (X4) + …                  Biết X2 là khí thải gây hiệu ứng nhà kính, X6...
Đọc tiếp

Cho các sơ đồ phản ứng:

(1) (X) + HCl ® (X1) + (X2) + H2O              

(2) (X1) + NaOH ® (X3)¯ + (X4)

(3) (X1) + Cl2 ® (X5)                                     

(4) (X3) + H2O + O2 ® (X6)¯                         

(5) (X2) + Ba(OH)2 ® (X7)                            

(6) (X7) + NaOH ® (X8) ¯ + (X9) + …

(7) (X8) + HCl ® (X2) +…                            

(8) (X5) + (X9) + H2O ® (X4) + …                 

Biết X2 là khí thải gây hiệu ứng nhà kính, X6 có màu đỏ nâu. Cho các phát biểu sau đây:

(a) Oxi hóa X1 bằng KMnO4 trong H2SO4 loãng thu được khí màu vàng lục.

(b) X5 vừa có tính oxi hóa, vừa có tính khử.

(c) X7 có tính lưỡng tính.

(d) X9 là hóa chất quan trọng trong công nghiệp thủy tinh, bột giặt, phẩm nhuộm, giấy, sợi....

Số phát biểu đúng là

A. 1

B. 2

C. 3

D. 4

1
15 tháng 7 2017

Chọn D.

(1) (X) FeCO3 + HCl ® (X1) FeCl2 + (X2) CO2 + H2O                   

(2) (X1) FeCl2 + NaOH ® (X3)¯ Fe(OH)2 + (X4) NaCl

(3) (X1) FeCl2 + Cl2 ® (X5) FeCl3                                                    

(4) (X3) Fe(OH)2 + H2O + O2 ® (X6)¯ Fe(OH)3                               

(5) (X2) CO2 + Ba(OH)2 ® (X7) Ba(HCO3)2   

(6) (X7) Ba(HCO3)2 + NaOH ® (X8) ¯ BaCO3 + (X9) Na2CO3 + …

(7) (X8) BaCO3 + HCl ® (X2) CO2 +…          

(8) (X5) FeCl+ (X9) Na2CO3 + H2O ® (X4)  NaCl …                      

Tất cả các ý trên đều đúng

19 tháng 10 2019

Đáp án B

29 tháng 7 2019

VIII. T×m lçi sai, gạch ch©n vµ söa l¹i cho ®óng trong c¸c c©u sau.1.There are two benchs in my room.                                                         ……………………2.Mr Hien isn’t lives in a house in the country.                           ……………………3.My mother is fourty years old.                                                    ……………………4. What color are her eyes?  It’s blue.                                                       ……………………5.Our classroom is on the three...
Đọc tiếp

VIII. T×m lçi sai, gạch ch©n vµ söa l¹i cho ®óng trong c¸c c©u sau.

1.There are two benchs in my room.                                                         ……………………

2.Mr Hien isn’t lives in a house in the country.                           ……………………

3.My mother is fourty years old.                                                    ……………………

4. What color are her eyes?  It’s blue.                                                       ……………………

5.Our classroom is on the three floor.                                                       ……………………

6. She often plays football in hers free time.                                ……………………

7. Hoa house is in the country.                                                                   ……………………

8. Our school is big. They have four floors.                                  ……………………

9. I go to school every mornings with my friends.                         ……………………

10. There is a hospital new near our school.                                 ……………………

IX. ChuyÓn sang sè nhiÒu c¸c c©u sau.

1. What’s this ?    It’s a bench.…………………………………………………………………………

2. Is that her knife? …………………………………………………………………………

3. This woman has a child. ………………………………………………………………………

4. The policeman is in his room.…………………………………………………………………………

5. Does he have a white tooth? 

2
25 tháng 3 2023

1.There are two benche​s in my room.                                                         ……………………

2.Mr Hien isn’t lives in a house thecountry.       ->doesn't

3.My mother is fourty_>forty years old.               

4. What color are her eyes?  It’s->they're blue.      

5.Our classroom is on the three->third floor.         

6. She often plays football in hers->her free time.    

7. Hoa's house is in the country.        

8. Our school is big. They->it have four floors.  

9. I go to school every mornings->morning with my friends.  

10. There is a new hospital  near our school.     

IX. ChuyÓn sang sè nhiÒu c¸c c©u sau.

1. What’s this ?    It’s a bench.…

what are these? they're benches

2. Is that her knife? are those her knives?……………

3. This woman has a child. …this woman has children/ these women have children

4. The policeman is in his room.…

the policemen are in their rooms……

25 tháng 3 2023

1.There are two benche​s in my room.                                                         ……………………

2.Mr Hien isn’t lives in a house thecountry.       ->doesn't

3.My mother is fourty_>forty years old.               

4. What color are her eyes?  It’s->they're blue.      

5.Our classroom is on the three->third floor.         

6. She often plays football in hers->her free time.    

7. Hoa's house is in the country.        

8. Our school is big. They->it have four floors.  

9. I go to school every mornings->morning with my friends.  

10. There is a new hospital  near our school.     

IX. ChuyÓn sang sè nhiÒu c¸c c©u sau.

1. What’s this ?    It’s a bench.…

what are these? they're benches

2. Is that her knife? are those her knives?……………

3. This woman has a child. …this woman has children/ these women have children

4. The policeman is in his room.…

the policemen are in their rooms……

17 tháng 7 2021

a) `(x^3-x^2)/(x^3-2x^2+x)`

`=(x^2(x-1))/(x(x-1)(x-1))`

`=x/(x-1)`

`=>` 2 phân thức bằng nhau.

b) `(x^2+2x+1)/(2x^2-2)`

`=((x+1)(x+1))/(2(x+1)(x-1))`

`=(x+1)/(2(x-1))`

`=(x+1)/(2x-2)`

`=>` 2 phân thức bằng nhau

a) Ta có: \(\dfrac{x^3-x^2}{x^3-2x^2+x}\)

\(=\dfrac{x^2\left(x-1\right)}{x\left(x^2-2x+1\right)}\)

\(=\dfrac{x\cdot\left(x-1\right)}{\left(x-1\right)^2}=\dfrac{x}{x-1}\)

b) Ta có: \(\dfrac{x^2+2x+1}{2x^2-2}\)

\(=\dfrac{\left(x+1\right)^2}{2\left(x+1\right)\left(x-1\right)}\)

\(=\dfrac{x+1}{2x-2}\)