\(\Rightarrow\dfrac{x}{2}=\dfrac{y}{3};\dfrac{y}{7}=\dfrac{z}{5}\) và \(3x+5x-7z=60\)

\(\Rightarrow\dfrac{x}{14}=\dfrac{y}{21};\dfrac{y}{21}=\dfrac{z}{15}\) và \(3x+5x-7z=60\)

\(\Rightarrow\dfrac{x}{14}=\dfrac{y}{21}=\dfrac{z}{15}\) và \(3x+5x-7z=60\)

\(\Rightarrow\dfrac{x}{14}=\dfrac{y}{21}=\dfrac{z}{15}=\dfrac{3x+5y-7z}{3.14+5.21-7.15}=\dfrac{60}{42}=\dfrac{10}{7}\)

\(\dfrac{x}{14}=\dfrac{10}{7}\Rightarrow x=\dfrac{10}{7}.14=20\)

\(\dfrac{y}{21}=\dfrac{10}{7}\Rightarrow y=\dfrac{10}{7}.21=30\)

\(\dfrac{z}{15}=\dfrac{10}{7}\Rightarrow z=\dfrac{10}{7}.15=\dfrac{150}{7}=21,428..\approx21,438...\)

Minh is my new classmate. He is now staying with his brother in Ha Noi, but he's from town and his parents still live there.

Minh's brother's house is smaller than his house in Bac Giang and it is on Xuan Thy Street. Our house is in the center of HN, so it is about kilometters, from his new house to school. Everyday Minh goes to school by bike. Minh is unhapy because he doesn't have many friends in HN. He also miss his parents and his friend, in Bac Giang.

I. Use given words to rewrite the second sentence that the meaning not change:

1. What a luxurious car!

How luxurious the car is !

2. It takes me an hour to do my homework every evening.

I spend an hour doing my homework every evening.

3. No one can run faster than me.

I am the fastest runner.

4. Is there a library at your school?

Does your school have a library ?

5. How old are you?

What is your age ?

6. Shall I bring you a cup of tea?

Would you mind if I brought you cup of tea ?

7. My sister is more hard-working than me.

I don’t work as hard as my sister ?

8. Do you have a better refrigerator ?

Is this the best refrigerator ?

9. Finding an apartment in a big city is not easy.

It is difficult to find an apartment in a big city.

10. February often has 28 days.

There are 28 days in February.

Đây là bài tớ tự làm, tham khảo

I like Physics. It's very interesting, because in Physics class, i can do some experiment, exercise, meditate, research, ... to broaden understanding. I am interested in Physics, it's not too difficult but it's very fun, peculiar i like star-gazing, i can research lots of star like Earth, Venus, Mercury, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. I always learn it every day from 10 PM to 1 AM. Thanks to it, i can research many start. Back to Physics, it need diagrams to understand much problem. Physicshave: Mechanics, Thermodynamics, Optics, Astronomy, Electricity, ... to we find news. So i love Physics, it is so interesting, new, difficult but it's very fun. I will do many Physical Exercises, how about you ? What's your hobby ?

Bài hình như ngắn quá

A hobby that I enjoy is using the computer. Surfing the internet is what I mostly do whenever I have free time. No one can deny the benefits of Internet. Information resources are probably the biggest advantage that Internet offers to people. Internet is wonderful source of information. All kind of information on any topic is available on the Internet at anytime. I love searching things on Google. It’s a very useful tool from the Internet, we can know everything with just one mouse click. Becoming knowledgeable is also a great benefit of using Internet. I spend a lot of time on the Internet for reading news. All latest news is continuously up-to-date on the Internet on various news sites. I often visit E-newspaper websites to read hot daily news. I can know everything such as current issues that happen in this world, what happen to our country, celebrities life, recent fashion, and other news that can enhance my knowledge. I would rather using Internet for updating news because it is available everywhere at anytime. In conclusion, people increasingly spend their leisure time using Internet because it is a helpful tool where people can learn new things and keep informed of information around the world. Internet turns the world into the speed generation. As the Internet saves us much time, we can have enough time to do other things. The internet is a marvelous creation in this generation.

Part 1 : Đặt câu hỏi :

A. His mother is a housewife.

A. What does his mother do ?

B. It takes me 10 munites to walk to school.

B. How much time do you have to go to school ?

Part 2 : Câu hỏi phụ :

- What will you do next weekend ?

+ I will do my homework next weekend.

Part 3 : Sắp xếp :

1. my/ class/ Nam/ is/ the/ in/ smartest/ boy.

Nam is the smartest boy in my class.

2. Nam/ will/ will/ but/ meet/ write/ mom/ his/ his/ friends/ not/ but/ he/ ,/.

Nam will meet his friend, but he will not write his mom.

(Câu này xem lại có đúng đề không nhé)

3. be/ at/ he/ home/ morning/ will/ tomorrw/ ?/

Will he be at home tomorrow morning ?

từ 1 -> 9 có số các chữ số là             1x[(9-1):1+1]=9(chữ số)

từ 10 -> 99 có số các chữ số là          2x[(99-10)/1+1=180(chữ số)

từ 100 ->128 có số các chữ số là        3*[(128-100)/1+1]=87_chữ số

từ 1 ->128 có số các chữ số là      9+180+87=276(chữ số)

ĐS

giải mỏi tay quá,bn mà ko tick mik thì tốn cả tgian của mik mất>_<

tick cho anh rồi anh giải chi tiết cho, dễ mà

How do you go to school ?

I go to school by wheelchair.

Cho dạng hoặc thì đúng của động từ trong ngoặc.

1. They (not go) don't go to the zoo very often.

2. I (not be) won't be at home next Monday evening.

3. Her father (work) works from the morning till night every day.

4. Mr. Robinson (look) is looking for an apartment at present.

5. There (be) is a few empty apartment near his office.

6. Hoa's parents love (work) working on their farm.

7. Is it easy (find) to find an apartment in Ha Noi?

8. Please tell her (call) call again later.