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15 tháng 4 2024

 

15 tháng 4 2024

Độ dài quãng đường là:

\(84:\left(\dfrac{1}{4}+\dfrac{1}{3}\right)=84:\dfrac{7}{12}=144\left(km\right)\)

vận tốc lúc về là 144:3=48(km/h)

15 tháng 4 2024

             Giải

Cứ một giờ người đó đi được: 1 : 4 = \(\dfrac{1}{4}\) (Quãng đường AB)

Cứ một giờ người đó về được: 1 : 3 = \(\dfrac{1}{3}\) (Quãng đường AB)

Cứ một giờ cả đi và về người đó đi được: 

\(\dfrac{1}{4}\) + \(\dfrac{1}{3}\) = \(\dfrac{7}{12}\) (Quãng đường AB)

Quãng đường AB dài là: 84 : \(\dfrac{7}{12}\) = 144 (km)

Vận tốc người đó đi từ B về A là: 144 : 3  = 48 (km/h)

Đáp số:  Quãng đường AB dài là 144 km

             Vận tốc người đó đi từ B về A là: 48 km/h

15 tháng 4 2024

Vận tốc lúc đi là 35-3=32(km/h)

Thời gian đi là 120:32=3,75(giờ)=3h45p

Cano đến B lúc:

7h25p+3h45p=11h10p

15 tháng 4 2024

Hiệu vận tốc hai xe là

60:3=20(km/h)

Hiệu số phần bằng nhau là 5-3=2(phần)

Vận tốc xe máy là 20:2x3=30(km/h)

Vận tốc ô tô là 30+20=50(km/h)

15 tháng 4 2024

Cám ơn bạn Thịnh

15 tháng 4 2024

\(P\left(1\right)=1^3-2\cdot a\cdot1+a^2=a^2-2a+1\)

\(Q\left(3\right)=3^2+\left(3a+1\right)\cdot3+a^2=a^2+9a+12\)

P(1)=Q(3)

=>\(a^2+9a+12=a^2-2a+1\)

=>11a=-11

=>a=-1

15 tháng 4 2024

x+y-3=0

=>x+y=3

\(M\left(x\right)=x^3+x^2y-3x^2-xy-y^2+4y+x+2020\)

\(=x^2\left(x+y\right)-3x^2-y\left(x+y\right)+4y+x+2020\)

\(=3x^2-3x^2-3y+4y+x+2020\)

=x+y+2020

=3+2020

=2023

15 tháng 4 2024

1. When I was young, I wanted to become a famous -------- and work with all the top models in Paris and Milan. A. computer programmer B. fashion designer C. shop assistant D. electrical engineer 2. Can you fix my printer for me? My office is ------ the third floor. The printer is ------- to my desk. A. on/next B. in/opposite C. at/next D. on/on 3. They ------- billions of dollars in the last decade in order to build mines and get the oil out of the ground. A. spend B. have spent C. spent D. had...
Đọc tiếp

1. When I was young, I wanted to become a famous -------- and work with
all the top models in Paris and Milan.
A. computer programmer
B. fashion designer
C. shop assistant
D. electrical engineer

2. Can you fix my printer for me? My office is ------ the third floor. The
printer is ------- to my desk.
A. on/next B. in/opposite C. at/next D. on/on

3. They ------- billions of dollars in the last decade in order to build mines
and get the oil out of the ground.
A. spend B. have spent C. spent D. had spent

4. Can you help me to ----- some -----? There are clothes on the floor and
the dishes need washing.
A. make/house work B. do/homework C.
do/housework D. do/favour

5. We would like to recruit three people for the positions of sales
representative. Email
info@hgmsales.com for a(an) ----------- form and
a full job description.
A. applicant B. contact details C. salary D.
application

6. The windows go transparent on buildings --------the sun shines brightly
and this will save on lighting bills.
A. who B. which C. where D. that

7. Jane: What social networking site are you using?
James: I’ve just ------ an account on Weibo. Facebook will be banned
in Vietnam, I guess.
A. searched B. subscribed C. uploaded D. set up

8. ------------ I get home, my cats usually ------ and rub their heads against
my feet.
A. When/come B. If/will come C. If/would come D.
When/would come

9. Peter: ---------------------------------
Tom: Just press the red button. You’ll see the screen appear right away.
A. What happens if I press this button?
B. How do you switch it on?
C. Why do you need to do that?
D. What is this for?

10. I don’t have a degree or anything like that, but I have learned lots of --
------ on the job.
A. qualifications B. timetable C. skills D. subjects

11. The school newsletter -------- until next week, so we don’t know the
new term dates.
A. doesn’t publish B. isn’t published C. will publish
D. will be published

12. A few years ago, the stone ---------- near to the old capital of an
ancient people called the Olmec.
A. discover B. discovered C. is discovered D. was
discovered

13. My family always ------------for celebrations and during the holidays.
A. get together B. pick up C. get along D. take away

14. Let me take your details and I’ll keep the place for you until the
weekend. -------, I’ll confirm it.
A. It’s very easy
B. After we’re received payment
C. To enrol
D. You can go online

15. The Outdoor Store can supply all your ----------- needs this summer
with high quality tents, cooking equipment and sleeping bags.
A. cruise B. catering C. camping D. sightseeing

16. Before I visited northern Norway, I --------- to many parts of the world,
including the southernmost point of Patagonia.
A. have been B. had been C. went D. have gone

17. On a clear day at the top, you get a spectacular view of the whole
mountain range. It has ----- views.
A. ancient B. unforgettable C. stunning D. legendary

18. Lots of people are ------- by the ride on rollercoasters at theme parks.
A. frightened B. frightening C. interested D. interesting

19. Engineers in the nineteenth century built these -------so barges could
carry goods on water from the factories to the cities.
A. canals B. tunnels C. subway station D. avenues

20. Passenger: Can you tell me --------------------------?
Ticket clerk: In about half an hour.
A. which train do I take to the city centre
B. which train I take to the city centre
C. what time does the next train leave
D. when the next train leaves

21. We ------------ take a holiday as a family because my parents were
always working.
A. usually B. used to C. didn’t used to D. didn’t use to

22. The archaeologists -------- this object was very important.
A. say B. said C. tell D. told

23. Go outside and do -------- interesting instead of watching TV all the
time.
A. something B. anything C. everyone D. somewhere

24. Unemployment, lack of education and crime are typical examples of --
------- problem.
A. economic B. natural C. social D. traditional

 

4
16 tháng 4 2024

1. When I was young, I wanted to become a famous -------- and work with
all the top models in Paris and Milan.
A. computer programmer
B. fashion designer
C. shop assistant
D. electrical engineer
2. Can you fix my printer for me? My office is ------ the third floor. The
printer is ------- to my desk.
A. on/next B. in/opposite C. at/next D. on/on
3. They ------- billions of dollars in the last decade in order to build mines
and get the oil out of the ground.
A. spend B. have spent C. spent D. had spent
4. Can you help me to ----- some -----? There are clothes on the floor and
the dishes need washing.
A. make/house work B. do/homework C.
do/housework
D. do/favour
5. We would like to recruit three people for the positions of sales
representative. Email info@hgmsales.com for a(an) ----------- form and
a full job description.
A. applicant B. contact details C. salary D.

16 tháng 4 2024

6. The windows go transparent on buildings --------the sun shines brightly
and this will save on lighting bills.
A. who B. which C. where D. that
7. Jane: What social networking site are you using?
James: I’ve just ------ an account on Weibo. Facebook will be banned
in Vietnam, I guess.
A. searched B. subscribed C. uploaded D. set up
8. ------------ I get home, my cats usually ------ and rub their heads against
my feet.
A. When/come B. If/will come C. If/would come D.
When/would come
9. Peter: ---------------------------------
Tom: Just press the red button. You’ll see the screen appear right away.
A. What happens if I press this button?
B. How do you switch it on?
C. Why do you need to do that?
D. What is this for?
10. I don’t have a degree or anything like that, but I have learned lots of --
------ on the job.
A. qualifications B. timetable C. skills D. subjects