Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
ta có
((x-a)(x-b))/((c-a)(c-b))+((x-b)(x-c))/((a-b)(a-c))+((x-c)(x-a))/((b-c)(b-a))=(( x-a)(x-b)(b-a)+(x-b)(x-c)(c-b)-(x-c)(x-a)(c-a))/((c-a)(c-b)(b-a))
=> mẫu là (c-a)(c-b)(b-a) (1)
ta có (x-a)(x-b)(b-a)
= (x-a)(x-b)( b-c+c-a)
=(x-a)(x-b)(b-c) + (x-a)(x-b)(c-a)
=> phần tử : (x-a)(x-b)(b-c)+ (x-b)(x-c)(c-b) + (x-a)(x-b)(c-a)- (x-c)(x-a)(c-a)
=(b-c)(x-b)(x-a-x+c) + (x-a)(c-a)(x-b-x+c)
=(c-a)(b-c)(x-b) +(x-a)(c-a)(c-b)
=(c-a)(c-b)(-x+b+x-a)=(c-a)(c-b)(b-a) (2)
từ (1);(2)=> tử/mẫu= ((c-a)(c-b)(b-a))/((c-a)(c-b)(b-a))=1 (đpcm)
Every ten minutes, one kind of animal, plant or insect dies out. for ever. If nothing is done about it, one million species that are alive today will have become extinct twenty years from now.
The seas are in danger They are being filled with poison: industrial and nuclear waste., chemical fertilisers and pesides, sewage. The Mediterranean is already nearly dead; the North Sea is following. If nothing done about it, one day soon nothing will be able to live in the seas.
The tropical rain forests, which are the origin of half the earth’s living things( including many rare animals and plants), are being destroyed. If nothing is done about it, they will have nearly disappeared in twenty years. The effect on the world’s climate – and on our agriculture and food supplies – will be disastrous.
Fortunately, somebody is trying to do something about it. In 1961, the World Wildlife Fund was founded - a small group of people who wanted to raise money to save animals and plants from extinction. Today, the World Wildlife Fund is a large international organisation. It has raised over 35 million pounds for conservation projects, and has created or given support five continents. It has helped 30 mammals and birds – including the tiger – to survive Perhaps this is not much, but it is a start. If more people give more money – and if more governments wake up to what is happening – perhaps the World Wildlife Fund will be able to help us to avoid the disaster that threatens the natural world, and all of us with it.
\(|x-1|=|x+2|\)
Nếu x>=1; ta có:
x-1= x+2 -> vô nghiệm
Nếu x<1 và x>=-2. ta có:
-x+1=x+2-> x=-1/2
Nếu x<-2; ta có
-x+1= -x-2 -> Vô nghiệm.
Vậy đáp số x=-1/2
| x - 1 | = | x + 2 |
Với x < -2 pt <=> -( x - 1 ) = -( x + 2 ) <=> -x + 1 = -x - 2 ( vô nghiệm :)) )
Với -2 ≤ x < 1 pt <=> -( x - 1 ) = x + 2 <=> -x + 1 = x + 2 <=> -2x = 1 <=> x = -1/2 ( tm )
Với x ≥ 1 pt <=> x - 1 = x + 2 ( vô nghiệm :)) )
Vậy phương trình có nghiệm duy nhất x = -1/2
D-WRITING:
Question VI. Make sentences, using the words and phrases provided (1.5point)
1. Tippping/ not/ custom/ Viet Nam/ so/ you/ not/ have/ tip/ if/ don’t want.
…………………Tipping is not a custom in Viet Nam, so you don't have to tip if you don't want to.………………………………………
2. In Brazil/ standard/ tip/ in/ restaurant/ be 10 percent.
………………………………In Brazil, the standard tip in restaurants is 10 per cent.……………………………….
3. The xoe dance/ performed/ the boys and girls/ the hamlets.
……………………The xoe dance was performed by the boys and the girls in the hamlets.……………………………………………
4. We/ have/take/ shoes/ when/ we/ inside/pagoda.
……………………We have to take oà your shoes when we go inside a pagoda.……………………………………….
5.Nowadays/ teenagers/ rely/ technology/ than/ the/ past.
…………………………Nowadays teenagers rely on technology more than in the past.……………………………..
6.Life/ the countryside/ changed/ a lot/ the/ ten /years.
………………………Life in the countryside has changed a lot over the past ten years.………………………………
ĐỀ SỐ 2
Question I. Find the word which has different sound in the part underlined. ( 1 point)
1. A. mention B. question C. action D. education
2. A. listened B. opened C. wanted D. lived
3. A. community B. computer C. museum D. customs
4. A. needed B. opened C. wanted D. decided
Question II. Choose the best answer A, B, C , or D to complete the sentences. (2. 5 points)
1. You should ____________ information about a custom or tradition.
A. finds B. found C. finding D. find
2. A tradition is something we do that is special and ____________ down through the generations.
A. to passed | B. passed | C. passing | D. is passing |
3. In the UK, there are lots of customs for table manners. For example, We ____________ use
a knife and fork at dinner.
A. have to B. are having C. has to D. having to
4. In Viet Nam, you____________ use only the first name to address people older than you.
A. should B. must C. shouldn’t D. have to
5. At the Mid-Autumn Festival ,kids can sing, dance, and enjoy moon-cakes ; ____________, every child s it very much.
A. However B. Moreover C. Because D. Therefore
6. In 2010, Ha Noi____________ its 1000th anniversary.
A. celebrated B. commemorated C. worshipped D. remembered
7. Tet is an occasion for family____________ in Viet Nam.
A. visitings B. Meeting C. reunions D. seeings
8. ____________ spring comes, many Vietnamese villages prepare for a new festival season.
A. While B. When C. Nevertheless D. However
9. People burn incense to show respect to their ____________ during Tet.
A. relatives B. ancestors C. friends D. neighbors
10. The Le Mat Festival ____________ the founding of the village.
A. worships B. commemorates C. performs D. preserves
Question III. Give the correct form of the following verbs: ( 2.0 points)
1. Peter ____________played ________ football yesterday. (play)
2. When I came, the whole family _________was having _____ dinner around a big dining table. (have) |
3. Children should______take_______ things from adults with both hands. (take) 4. My father and I ___get_______ up at 5 o’clock every morning. (get) 5. They ______are learning___________ English at the moment. ( learn) 6.We ______________went______ to Hung King Festival since last Sunday. (go) 7. Before leaving the dinner table, _____does____your son _____have to___ ask for permission? (have to) 8.When I _____came______ ,the whole family was having dinner around a big dining table. (come) |
Circle the best word/phrase (A,B,C or D) to complete the sentences below.
1, Australia is composed of seven _____ .
A. nations B. countries C. states D. capitals
2, _____ you ever been to any English speaking countries ?
A. Do B. Have C. Were D. Are
3, What can be done to protect people from _____ disasters?
A. environment B. environmental C. environmentally D. environmentalist
4, __________ should we meet on Sunday ? - Because I have to do some shopping first, then let's meet at 10 a.m
A. Why B. Where C. What time D. When
5, By the time we got to the cinema, the film ______.
A. started B. had started C. starting D. starts
6, A person who _______ the bagpipes is called a piper.
A. plays B. performs C. entertains D. brings
7, Don't drink that water. It's ______.
A. damaged B.dumped C. contaminated D. disppeared
8. The team's succes was largely ____ to her efforts.
A. because B. due C. since D. although
9. If you ______ the president, what would you do to help the environment ?
A. are B. had been C. were D. have
10, - " I've passed my driving test."
- " _____"
A. Congratulations! B. That's a good idea. C. It's nice of you to say so. D. Do you ?
Circle the best word/phrase (A,B,C or D) to complete the sentences below.
1, Australia is composed of seven _____ .
A. nations B. countries C. states D. capitals
2, _____ you ever been to any English speaking countries ?
A. Do B. Have C. Were D. Are
3, What can be done to protect people from _____ disasters?
A. environment B. environmental C. environmentally D. environmentalist
4, __________ should we meet on Sunday ? - Because I have to do some shopping first, then let's meet at 10 a.m
A. Why B. Where C. What time D. When
5, By the time we got to the cinema, the film ______.
A. started B. had started C. starting D. starts
6, A person who _______ the bagpipes is called a piper.
A. plays B. performs C. entertains D. brings
7, Don't drink that water. It's ______.
A. damaged B.dumped C. contaminated D. disppeared
8. The team's succes was largely ____ to her efforts.
A. because B. due C. since D. although
9. If you ______ the president, what would you do to help the environment ?
A. are B. had been C. were D. have
10, - " I've passed my driving test."
- " _____"
A. Congratulations! B. That's a good idea. C. It's nice of you to say so. D. Do you ?
Ex1: Choose the best answer:
Question 1: Do you know what is the cause __________ pollution?
A. of B. in C. on D. for
Question 2: My mother has to measure blood __________ every month
A. billboard B. pressure C. groundwater D. earplug
Question 3: __________ pollution is harmful or annoying level of noise, as from vehicles, industry activities, etc.
A. light B. visual C. soil D. noise
Question 4: Parents should teach children not to __________ wastes on the road
A. litter B. poison C. cause D. measure
Question 5: I can’t hear your voice __________ I’m wearing an earplug
A. although B. due C. however D. because
Question 6: His grandfather made him __________ hard when he was small
A. study B. to study C. studying D. studied
Question 7: This picture __________ the contamination of ground water.
A. illustrate B. illustrating C. illustrates D. illustrated
Question 8: Could you list some non-point source __________?
A. pollution B. pollutants C. polluting D. polluted
Question 9: Scientists has just come up __________ a solution to hearing loss
A. to B. on C. with D. down
Question 10: If we dump a plas into the ground, it __________ a long time to disappear.
A. will take B. take C. took D. takes
Question 11: Pollutions are harmful __________ human health
A. with B. at C. to D. on
Question 12: __________ water resulted in the death of many aqua animals.
A. Contaminate B. Contaminated C. Contaminating D. Contamination
Question 13: What would you do if a factory in your neighborhood __________ untreated water into the river?
A. dump B. dumped C. dumping D. dumps
Question 14: Have you ever heard about the __________ of radioactive pollution?
A. affects B. effects C. pollutes D. poisons
Question 15: : __________ pollution is the increase of temperature caused by human activity.
A. visual B. water C. thermal D. radioactive
Ex2: Supply the correct form of the verbs in brackets
1. Lan often (do) ____does______ her homework.
2. They (play) ______are playing____ tennis now.
3. Lan (buy) ___has bought______ a car since 2000.
4. Minh (watch) ___watched____ TV last night.
5. Hoa (meet) ____will meet_____ Lan tomorrow.
6. Football (play) _____is played___ by boys.
Chào em, em tham khảo nhé!
Ex3: Find and correct mistakes:
1.What about watch TV?
A. What B. about C. watch => watching
2.Do you mind if I listened to music?
A. mind B. listened => listen C. to
3.What do you do yesterday?
A. What B. do => did C. yesterday
4.My dog is different with her dog.
A. is B. with => from C. her
Ex4: Rewrite sentences without changing the meaning.
1. Let’s go to the zoo!
What about going to the zoo?
2. Ba enjoys skipping.
Ba s skipping/to skip.
3. Long should work harder.
Long ought to work harder.
4. Would you mind opening the door?
Do you mind opening the door?
4. I can’t tell you unless you tell me what’s wrong. (if)
-> If you don't tell me what's wrong, I can't tell you.
5. Nhung didn’t go to the cinema with her friends because her younger sister was ill.
-> Because of her illness, Nhung didn't go to the cinema with her friends.
6. Eating too much sugar can result in health problem. (lead to)
-> Eating too much sugar can lead to health problem.
7. Minh isn’t hard-working, so he often gets bad marks. (if)
-> If Minh were hard-working, he wouldn't get bad marks.
8. I’m not you. But I think you should recycle these plas carrier bags. (If)
-> If I were you, I would recycle these plas carrier bags.
Ex5: Use the correct form of the words given to complete the sentences.
1. This volcano is dead; it has been (ACT) inactive for more than a century.
2. The Earth would be a happy planet if human beings, animals and plants (PEACE) peacefully co-existed.
3. The chemical (POLLUTE) pollutant from cars and factories make the air, water and soil dangerously dirty.
4. You cannot imagine how (SERIOUS) serious the area was damaged by the flood.
5. Scotland is a legendary land and this is noted for its rich and interesting history. (legend)
Chúc em học tốt và có những trải nghiệm tuyệt vời tại olm.vn!
-Dạng 1: Phương trình tích.
a) \(2x\left(x+1\right)=x^2-1\)\(\Leftrightarrow2x\left(x+1\right)=\left(x-1\right)\left(x+1\right)\)
\(\Leftrightarrow2x\left(x+1\right)-\left(x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(2x-x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)^2=0\)
\(\Leftrightarrow x+1=0\Leftrightarrow x=-1\)
Vậy phương trình có nghiệm duy nhất : x = -1
b) \(x^3+3x^2-2x-2=0\)\(\Leftrightarrow\left(x^3-x^2\right)+\left(4x^2-4x\right)+\left(2x-2\right)=0\)
\(\Leftrightarrow x^2\left(x-1\right)+4x\left(x-1\right)+2\left(x-1\right)=0\)
\(\Leftrightarrow\left(x^2+4x+2\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[\left(x+2\right)^2-2\right]\left(x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}\left(x+2\right)^2-2=0\\x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}\left(x+2\right)^2=2\\x=1\end{cases}}}\)
Xét phương trình \(\left(x+2\right)^2=2\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=\sqrt{2}\\x+2=-\sqrt{2}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\sqrt{2}-2\\x=-\sqrt{2}-2\end{cases}}}\)
Vậy phương trình có tập nghiệm : \(S=\left\{1;\pm\sqrt{2}-2\right\}\)
Dạng 2 ; Phương trình chứa ẩn ở mẫu.
\(\frac{3}{1-5x}+\frac{5}{3-5x}=\frac{x-27}{\left(5x-1\right)\left(5x-3\right)}\left(ĐKXĐ:x\ne\frac{1}{5};x\ne\frac{3}{5}\right)\)
\(\Leftrightarrow\frac{3}{1-5x}+\frac{5}{3-5x}=\frac{x-27}{\left(1-5x\right)\left(3-5x\right)}\)(phần này bạn nhớ đọc kĩ bên vế phải)
\(\Leftrightarrow\frac{3\left(3-5x\right)}{\left(1-5x\right)\left(3-5x\right)}+\frac{5\left(1-5x\right)}{\left(3-5x\right)\left(1-5x\right)}=\frac{x-27}{\left(1-5x\right)\left(3-5x\right)}\)
\(\Rightarrow3\left(3-5x\right)+5\left(1-5x\right)=x-27\)
\(\Leftrightarrow9-15x+5-25x=x-27\)
\(\Leftrightarrow14-40x=x-27\)
\(\Leftrightarrow-40x-x=-27-14\)
\(\Leftrightarrow-41x=-41\)
\(\Leftrightarrow x=1\)(thỏa mãn ĐKXĐ)
Vậy phương trình có nghiệm duy nhất : x = 1.