bạn nhân chéo lên nhé : \(\Rightarrow-2\left(-18\right)=26x\Rightarrow26x=36\Rightarrow x=\frac{13}{18}\)

gọi x₁= căn 2+căn3;x₂=căn2-căn3

S=x₁+x₂=2căn2

P=x₁*x₂=-1

áp dụng viét ta được pt

x²-Sx-P=0

Toán nâng cao lớp 7 đã khó nhăn răng rùi mà đây còn Toán nâng cao 8 ^._^.

Vậy vì sao sự cháy trong không khí diễn ra chậm hơn sự cháy trong khí oxi?

Trong không khí, diện tích tiếp xúc của chất cháy đối với các hạt oxi ít hơn so với khí oxi. Dẫn đến sự cháy trong không khí diễn ra chậm hơn trong oxi Điều này cũng làm cho nhiệt độ của sự cháy trong khí oxi cao hơn (vì một phần nhiệt tiêu hao để đốt nóng các hạt khác.).

Tiền Dũng bằng 6/5 tiền Nam

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I. Choose the best words by circling A, B, C or D.

Question 1: My freinds like listening ...........................the latest pop music.

A. on B. of C. to D. for

Question 2: Hoa ..................... to the school theater club last night.

A. to go B. go C. went D. goes

Question 3: She is 145 centimeters ...........................

A. heavy B. tall C. high D. old

Question 4: If you are interested ..................... history, you could visit many ancient monuments.

A. in B. at C. on D. of

Question 5: A: What do you do in the evening? – B: ...........................

A. I am watching TV B. I will watch TV C. I often watch TV D. I watched TV

Question 6: She doesn't like pork, and ...........................does her uncle.

A. neither B. so C. too D. either

Question 7: We should .................morning exercise.

A. does B. do C. to do D. doing

Question 8: He...........................busy yesterday and so were his brothers.

A. were B. was C. are D. is

Question 9: You must ......................much water every day.

A. drink B. to drink C. drinking D. drinks

Question 10: I would like ...........................some fruit and vegetables.

A. buys B. bought C. to buy D. buying

Question 11: A: Where are you going, Phong?

B: I....................... to school.

A. is going to go B. go C. goes D. am going to go

Question 12: How ................are you? I'm 40 kilos

A. far B. many C. heavy D. tall

II. Choose one word whose underlined part is pronounced differently from others

Question 13: A. ripe B. slice C. diver D. spinach

Question 14: A. better B. rest C. pretty D. wet

Question 15: A. subject B. uniform C. music D. computer

Question 16: A. apartment B. party C. marbles D. favorite

III. Complete the sentences, using the correct forms of verbs in brackets

Question 1. My uncle (play) ......plays............ chess everyday.

Question 2. You ought to (repair) ....reapair.......... your bike before going to school.

Question 3. You ought to (repair) .......repair....... your bike before going to school.

Question 4. Linh will (visit).......visit..... grandmother tomorrow morning.

IV. Read the dialogue. Then choose the best answer

In 1960s, most people in Vietnam did not have a TV set. In the evening, the neighbors gathered around the TV. They watched until the TV programs finished. The children might play with their friends and the older people might talk together. Vietnam is different now. Many families have a TV set at home and the neighbors don't spend much time together.

Question 1. Did most people have a TV set in 1960s?

.....No,they did..............

Question 2. How long did they watch TV programs?

........They watched until the TV programs finished. .......

Question 3. What might the children do?

......The children might play with their friends .......

Question 4. What might the older people do?

.......... The older people might talk together. .........

V. Complete the sentences.

Question 1. Would/ like/ to play/ you/ chess/?

.....Would you like to play chess?...........

Question 2. Students/ play/ outdoors/ should

......Students should play outdoors .......

Question 3. What/ going/ about/ to/ the movie theater.

....What about going to the movie theater?.........

Question 4. Why/ we/ go/ Ha Long Bay/ don't/ to?

.......Why don't we go to Ha Long Bay?..........

1/ The weather focast is on TV. "Can you turn up the volume?"

-"................ ."

A. I hope so B. That's a good idea

C. Yes, I think so,too D. You are welcome

2/ You like watching sports,don't you?

A. I'm the opposite B. I think so

C. Yes, I like D. No, I hate it

PUT THE VERB INTO THE CORECT FORM

1. The traffic was very heavy. By the time I got (get) to Linda's party, everyone had already arrived (already arrive).

2. I'll graduate in June, I will see (see) you in July. By the time I see (see) you, I will have graduated (graduate).

3. Behave yourself, Lucy. If you do (do) that again, you will have (have) to go to bed.

4. When Alice got(get) here, did you show (show) her to her room?

5. As Hugh and I come (come) down the steps we nearly run (run) into my father.

6. I think (think) about you a lot lately and I will come (come) to the conclusion that I will not be (be not) able to live without you.

7. I don't mind waiting (wait). I'd rather be (be) too early than too late.

8. I think your garden needs weeding (weed). And you'd better have (have) it done tomorrow.

9. Woul your children mind being kept (keep) quiet for a moment? I'm trying to fill (fill) in a form.

10. Hurry up or our favourite TV programmer will be (be) over long before we reach (reach) home.

11. We came to sit on a park bench for a rest. We had shopped (shop) around all morning and bought (buy) a lot of food.

12. I think (think) your father's health has improved (improve) so much since I saw (see) him last.

nối các vế câu

1.let‘s go to Ben Thanh maket

2.do you mind if smoke here?

3.do you like leaning English?

4. can you lend me your motorbike

a.that‘s a good idea!

b.yes of course

c. please go to ahead

d.yes,very much

e.no,thanks

Đáp án: 1->a 2->c 3-> d 4-> b

-4/8=-12/24=z/24. Suy ra z=-12

-4/8=-1/2=5/-10=x/-10. Suy ra x=5

-4/8=-1/2=-7/14=-7/y. Suy ra y=14

Ủng hộ mk nha, mãi chưa đc nào cả !!