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3 tháng 4 2020

Chứng minh gì vậy bạn?

3 tháng 4 2020

a) \(\hept{\begin{cases}2.\left(m-1\right).x-2.m.y=6m-2\\2.\left(m-1\right).x-\left(m-1\right).y=\left(m-1\right).\left(m+5\right)\end{cases}}\)

=> -2.m.y + ( m-1 ) .y = 6m - 2- ( m2 - m + 5.m -5 ) 

=> ( -m - 1 ) . y = -m2 + m + 2 

hay y = \(\frac{m^2-m-2}{m+1}=\frac{\left(m+1\right).\left(m-2\right)}{\left(m+1\right)}\)

         = m - 2 

Với m \(\ne\)-1 => y = m- 2 

Khi đó x = \(\frac{m+5+y}{2}=\frac{m+5+m-2}{2}=\frac{2m+3}{2}\)

b) \(\hept{\begin{cases}y=\left(m+5\right)+2.x\\m.y=\left(3.m-1\right)-\left(m-1\right).x\end{cases}}\)hay \(\hept{\begin{cases}y=2.x-\left(m+5\right)\\y=\frac{-\left(m-1\right).x+\left(3m-1\right)}{m}\end{cases}}\)

Vậy để hai đường thẳng của hệ cắt nhau cho giá trị nằm ở góc phần tư thứ IV của Oxy => \(\hept{\begin{cases}x>0\\y< 0\end{cases}}\)

=> \(\hept{\begin{cases}x< \frac{m+5}{2}\\x>\frac{3m-1}{m-1}\end{cases}\Rightarrow\hept{\begin{cases}m>3\\m< 6\end{cases}\Rightarrow}\hept{\begin{cases}m=4\\m=5\end{cases}}}\)( Mình cũng không chắc phần này ở đoạn đầu tiên nha ) 

Cô-rô-na * Thứ kì lạ Ngôi nhà chung màu xanh của chúng taSao bỗng nhiên xuất hiện một người lạEm đến đây chẳng được ai chào đónMà lại khiến mọi người phải tránh xa.Không gì khác chính là cô-rô-naToàn dân lo lắng, từ trẻ đến giàCả nước ta cùng tích cực phòng chốngVà tốt nhất là mọi người ở nhà.Te-le-phone là vật bất li thânNay khẩu trang luôn đeo chẳng ngại ngầnNước rửa tay...
Đọc tiếp

Cô-rô-na * Thứ kì lạ 
Ngôi nhà chung màu xanh của chúng ta
Sao bỗng nhiên xuất hiện một người lạ
Em đến đây chẳng được ai chào đón
Mà lại khiến mọi người phải tránh xa.

Không gì khác chính là cô-rô-na
Toàn dân lo lắng, từ trẻ đến già
Cả nước ta cùng tích cực phòng chống
Và tốt nhất là mọi người ở nhà.

Te-le-phone là vật bất li thân
Nay khẩu trang luôn đeo chẳng ngại ngần
Nước rửa tay và thêm cồn sát khuẩn
Trọn com-bo giúp chúng ta phòng thân.

Em hình như có nhẫn thuật phân thân
Từ số một nhân lên gấp ngàn lần
làm con người ai ai cũng sợ hãi
Nhưng đừng vậy mà khiến ta chùn chân.

Đất nước ta đồng lòng cùng chống dịch
Như thời chiến còn đang đánh giặc minh
Nhưng chiến tranh chẳng có đạn và súng
Và bác sĩ người quyết chiến đến cùng.

Người VIệt Nam phải yêu nước thương dân
Đi cách li chẳng một chút ngại ngần
Mong một ngày ta chiến thắng đại dịch
Đất nước ta trở lại buổi bình yên.
Điền

Làm tí thơ ủng hộ phòng chống co-rô-na cả nhà ơi!!

2
31 tháng 3 2020

bn ei ko đăng linh tinh

hc tốt

31 tháng 3 2020

1 . Không được đăng linh tinh , vớ vẩn .

2 . Không hề có câu hỏi ở đây cả .

học tốt nha

rade 9ConditionalChoose the best answer1._____have enough apples, she’ll make an apple pie this afternoon.A.Should sheB. If sheC. Will sheD. Unless she2.If you_____to me, you wouldn’t have got so much trouble.A.listenedB. would listenC. had listenedD. Would have listened3.If you don’t know how to spell a word, you_____ look it up in the dictionary.A. mustB. willC. shouldD. ought4.If the sun _____, we _____for a walk.A. shines / will goB. shone / willgoC. shone / would go D. had shone /...
Đọc tiếp

rade 9

Conditional

Choose the best answer

1.

_____have enough apples, she’ll make an apple pie this afternoon.

A.Should she

B. If she

C. Will she

D. Unless she

2.

If you_____to me, you wouldn’t have got so much trouble.

A.

listened

B. would listen

C. had listened

D. Would have listened

3.

If you don’t know how to spell a word, you_____ look it up in the dictionary.

A. must

B. will

C. should

D. ought

4.

If the sun _____, we _____for a walk.

A. shines / will go

B. shone / will

go

C. shone / would go D. had shone / would go

5.

The campfire _____ if it _____ last night.

A. wouldn’t be cancelled / hadn’t rained

B. wouldn’t have been cancelled / hadn’t rained

C. would have been cancelled / hadn’t rained

D. will be cancelled / rains

6.

But for our parents, we _____ successful in life.

A. will never be B. would never be C. wouldn’t have be

D. would have never been

7.

If I _____ my wallet at home this morning, I _____ money for lunch now.

A. leave / will have

B. didn’t leave / would hav

e

C. hadn’t left / would have

D. hadn’t left / would have had

8.

It is too bad, Lam isn’t here. If he _____ here, he _____ what to do.

A. were / would know

B. is / will know

C. had been / would have known

D. was / would know

9.

If we _____ the plans

carefully, we would not have had so many serious mistakes.

A. study

B. had studied

C. studied

D. were studying

10.

I will never talk to you again _____ you apologize me _____ your being rude.

A. if / for

B. unless / for

C. or / of

D. whether / or

11.

_____

i

f you work harder, you will be sacked.

A. Whether

B. If

C. However

D. Unless

12.

I think you should stop smoking.

A. If I am you, I will stop smoking.

B. If I were you, I will stop smoking.

C. If I were you, I would stop smoking.

D. If I had been you, I wo

uld stop smoking.

13.

If you take the ice out of the fridge, it

_____.

A. vaporizes

B. melts

C. heats

D. disappears

14.

We should do something to protect water from being polluted

_____

we will have nothing

to drink in the future.

A. if

B. whether

C. or

D. un

less

15.

Let’s knock on their door to see

_____

home.

A. if they’re

B. unless they’re

C. whether they were

D. if they were

16.

Unless we

_____

more snow, we can’t go skiing.

A. will have

B. have

C. have had

D. had

17.

You’ll fail the exam

_____

you start revis

ing.

A. if

B. until

C. when

D. unless

18.

Unless you wash the car, you

_____

not drive it at the weekend.

A. would

B. could

C. have to

D. may

19.

If Peter

_____

his car before the drive, he

_____

the problem of out of petrol.

A. checked / will not get

B. had checked / would not have got

C. checks / will not have got

D. would be checking / will not have got

20.

He stepped on the mine, and it exploded.

A.

If he doesn’t step on the mine, it doesn’t explode.

B.

If he doesn’t step on the mine, it won’t explode.

C.

If he didn’t step on the mine, it wouldn’t explode.

D.

If he hadn’t stepped on the mine, it wouldn’t have exploded.

21.

In my experiments, the liquid is cooled to 32

ºF. It always freezes.

A.

If you cool the liquid to 32 degrees, it froze.

B.

If you cooled the liquid

to 32 degrees, it would freeze.

C.

If you cool the liquid to 32 degrees, it will freeze.

D.

If you had cooled the liquid to 32 degrees, it would have frozen.

22.

It may rain this afternoon. I hope it doesn’t because I don’t want the match to be

canceled.

A. If

it rains, the match is canceled.

B. If it rains, the match will be canceled.

C. if it rained, the match would be canceled.

D. If it had rained, the match would have been canceled.

23.

Unfortunately, I don’t know Philosophy, so I can’t answer your question.

A.

If I know Philosophy, I can answer your question.

B.

If I know Philosophy, I will be able to answer your question.

C.

If I knew Philosophy, I would be able to answer your question.

D.

If I had known Philosophy, I would have been able to answer your question.

24.

_____

there are some more ideas, we can end the meeting now.

A. If

B. As if

C. Unless

D. In case

25.

If he

_____

with us now, he

_____

the beauty of nature of the National Park.

A. is / can enjoy B. was / will enjoy

C. has been / would enjoy D. were / could

enjoy

26.

If they had searched more carefully, they...the watch sooner.

A. will find

B. would find

C. found

D. would have found

27.

If I had got up early, I _____ to have breakfast now.

A. have

B.I had

C. would have

D. would have had

28.

I cannot buy a new co

mputer _____ I save enough money.

A. if

B. even if

C. unless

D. as if

29.

Most people you meet will be polite to you _____.

A. if you are polite to them

B. if you will be polite to them

C. unless you are polite to them

D. if you were polite to them

30.

If

you do so, it _____ the matter worse.

A. makes only

B. would only make

C. will only make

D. had only made

31.

You _____ English fluently unless you practice it every day.

A. will speak

B. will not speak

C. can speak

D. did not speak

32.

Hurry up _____ you will

miss the bus and be late for school.

A. if

B. and

C. or

D. as

33.

You will get a good seat if you _____ first.

A. come

B. came

C. have come

D. will come

34.

Mary

will not graduate_____.

A. if he passed all the tests

B. if he does not pass all the tests.

C. unless he passes all the tests

D. unless he had passed all the tests.

35.

If I had time, I would go with you.

A.I am free and surely go with you.

B.I am too busy to go with you.

C. I will go with you because I have time.

D. I am free enough to go with

you.

36.

If

San

dra

hadn’t been wearing a seat belt, she.... Injured.

A. has been

B. would has been

C. would be

D. would have been

37.

If I _____ the rain yesterday, I_____ ill.

A. had not caught / would have been

B. had not caught / would have not been

C. have n

ot caught / were not

D. have not caught / would have been

38.

He looked frightened as if he _____ a ghost.

A. sees

B. is seeing

C. has seen

D. had seen

39.

What _____if there _____ a serious nuclear accident.

A. will happen / was

B. happens / were

C. woul

d happen / were

D. would happen / had been

40

.

Linda

will not go to the party unless

her sister

..................

.too.

a. go

b. went

c. going

d. goes

1
16 tháng 4 2020

1b 2a 3c 4a 5b 6a 7b 8a 9b 10a 11bỏ 12c 13d 14d 15a 16b 17d 18d 19b 20c 21c 22b 23d 24c 25d 26d 27d 28c 29s 30c 31b 32c 33a 34c 35b 36d 37b 38a 39c 40d

(ý kiến cá nhoân của iem nhoa) thích thì tích (t  i  c  k)