áp dụng tính chất dãy tỉ số bằng nhau ta có:

\(\frac{a}{4}=\frac{b}{6}=\frac{c}{7}=\frac{a^2}{16}+\frac{b^2}{36}-\frac{c^2}{49}=\frac{a^2+b^2-c^2}{16+36-49}=\frac{12}{3}=4\)

vậy:
a/4=4 =>a=4.4=16

b/6=4 =>b=4.6=24

c/7=4 =>c=4.7=28

I.Choose the best options to complete the sentencces

1.She ....... a picnic with friends next week.

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

2.People ....... the environment if they ....... or cycle more

A.help-will walk B.help-walk C.will help walk

3.If plants ...... more, we ....... enough food to feed everyone.

A.die-will have B.die-won't have C.will die-won't have D.won't die-won't have

4.She ....... until midnight tomorrow because it is important

A.will not work B.might work C.will work D.can work

5.If Mai ........ trees and flowers in her garden, it ........ greenner and more beautiful

A.grow-will be B.grows-will be C.grow-won't be D.-won't be

6.I.......... my son for a a long time. He hasn't visited my since May

A.have seen B.hasn't seen C.haven't seen D.has seen

7. If the river is.........., many fishes.....

A.polluted-will die B.polluted-dies C.is polluted-dies D.is polluted-will die

8.If people ....... the rubbish, it ...... harmful smoke .

A.burn-will produce B.burns-will produce C.will burn-produce D.will burn-produces

ENGLISH TEST 06

I. Pick out the word whose underlined part in pronounced differently from

1.

A.

beach

B.

seat

C.

meat

D.

great

2.

A.

boots

B.

floor

C.

toothpaste

D.

food

3.

A.

idea

B.

year

C.

wear

D.

near

4.

A.

camp

B.

plan

C.

plane

D.

badminton

5.

A.

maps

B.

beds

C.

rooms

D.

taxis

6.

A.

full

B.

summer

C.

sunny

D.

Sunday

7.

A.

orange

B.

hot

C.

hobby

D.

nose

8.

A.

sometimes

B.

washes

C.

benches

D.

couches

9.

A.

ride

B.

night

C.

river

D.

tired

10.

A.

teeth

B.

tree

C.

between

D.

engineer

II. Choose the best answer

1. There are...................eggs in the fridge.

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

2. What do you do .............................the weekend.

A. on B. in C to D. for

3. I am going .........Ha Long bay

A. visiting B. visit C. visited D. to visit

4. There isn’t _______milk in the bottle.

A. an B. a C. any D. some

5. How much is a _________of toothpaste.

A. can B. bar C. tube D. box

6. What about ______table-tennis?

A. to play B. playing C. plays D. play

7. Fall means …………

..in British-English.

A. summer B. winter C. autumn D. spring

8. What is her _____________? _ She is Australian.

A. language B. nationality C. population D. country

9. They are going _________vacation in London.

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

10. ________languages can you speak?

A. When B. How C. How much D. Which

11. The Great Wall of China is the world’s _____structure.

A. long B. longer C. the longest D. longest

12. Ho Chi Minh has a ___________of 3.5 million.

A. city B. capital C. population D. country

13. I am Mary. I am __________ Great Britain.

A. to B. from C. at D. on

14. ______are you going to stay? _ In a hotel.

A. Which B. Where C. When D. What

15. Tomatoes, lettuce and potatoes are …………

A. fruits B. vegetables C. drinks D. flowers

16. There is an intersection ahead. You must______ .

A. slow down B. go fast C. stop D. go ahead

17. There isn’t any water in the bottle. I am going to take ______.

A. many B. an C. any D. some

18. A. What is the matter with you? – B: ______

A. I go by bike B. I’m heavy C. I like chicken D. I’m tired

19. A: Would you like a glass of lemon juice? – B: ______

A. No, I’m not B. No, I don’t like C. No, thanks D. No. It’s too hot.

20. PETRONAS Twin Towers is the…………. building in the world.

A. tall B. taller C. tallest D. the tallest

21. Mai needs …………

chocolates.

A. a bar of B. a packet of C. a box of D. a bottle of

22. He …………

his bicycle at the moment.

A. rides B. is riding C. ride D. to ride

23. Phanxipang is the …………

mountain in Viet nam.

A. high B. higher C. highest D. the highest

24…………

is the weather like?

A. How B. What C. Who D. How much

25.My house is as …………

as Hoa’s house.

A. smaller B. small C. biggest D. bigger

26.We …………

waste food and feed it to pigs.

A. damage B. collect C. leave D. throw

27.Chi is…………

girl in her class.

A. more beautiful B. the most beautiful C. beautiful D. a most beautiful

28.I’m going …………

the Ngoc Son Temple tomorrow

A. see B. sees C. to see D.seeing

29.What …………

you

to do tomorrow?

A. does / go B.is / going C.are / going D. do / go

30. We shouldn’t ………… our environment.

A. destroying B. to destroy C. destroys D. destroy

31. He often ________ he ________ the kites when he isn’t busy?

A. does / flies B. does / fly C. does / play D. does / play

32. Why don’t we ________ to the movies? ~ That’s a good idea.

A. go B. to go C. going D. to going

33. Some people can speak many ________

A. countries B. nationalities C. languages D. speeches

34. There are four ________ in a year: spring, summer, fall and winter.

A. activities B. pastimes C. weathers D. seasons

35. Can I help you? ~ ________ please. I need a kilo of beef.

A. Yes B. Sorry C. Can D. No

36. Mr Thanh is a policeman. He has a …………

.job

A. fast B. careful C. difficult D. bad

37. Her sister has an…………face and long black …………

A. round - hairs B. long - hairs C. oval -hair D. oval - hairs

38. What are ………? ………

..are his shoulders

A. those-These B. those-Those C. this-This D. those-This

39. How many oranges, Mom? ……… dozen, please

A. A half of B. Half a C. A half D. Half

40.You ……… eat too much meat. It isn’t good for your health.

A. should B. shouldn’t C. not D. don’t want

Ta có: 9¹¹+1=9^2.5+1+1

                   =(9²)⁵.9+1

                   =81⁵.9+1

                  =(...1).9+1

                  =(...9)+1

                  =(...0)

Mà số có CSTN = 0 chia hết cho cả 2 và 5

=>9¹¹+1 chia hết cho cả 2 và 5(đpcm)