mk thấy nó toàn liên quan đến lớp 12

tóm tắt:

20 ngày: 120 người

25 ngày:.......người?

giải:

số người ăn trong 25 ngày là:

20 x 120 : 25 = 96 (người)

vậy số người đã chuyển đi là:

120 - 96 = 24 (người)

ĐS: 24 người

1 đúng nhé

2. My name is Mai.

3. How is she?

4. Minh is all right.

5. Lan and I are10 years old.

6. She is Lan. She is thirteen.

7. Mai is a student.

8.How old are they.

9. They are Ba and Nam.

10. We are play fotball.

11. He is my brother.

12. They are student.

13. Rex is a lively dog.

14. I am a boy. 

Ta có: \(\frac{x}{4}=\frac{y}{7}=k\)

\(\Rightarrow x=4k\); \(y=7k\)

Theo đề bài ta có:

\(xy=112\)

\(\Rightarrow4k\cdot7k=112\)

\(28k^2=112\)

\(k^2=4\)

\(\Rightarrow k=\pm2\)

\(\Rightarrow x=8\); \(y=14\)

\(\Rightarrow x=-8\); \(y=-14\)

Vậy \(\left(x;y\right)\in\left\{\left(8,14\right);\left(-8,-14\right)\right\}\)

Gọi quý 3 là A

\(\Rightarrow A\in\left\{7;8;9\right\}\)

Ta có: A = (-2) +(-2)³ + (-2)⁵ + . . . + (-2)¹⁰¹

=> (-2)²A = (-2)³ + (-2)⁵ + . . . + (-2)¹⁰³

     4A - A= (-2)³ + (-2)⁵ + . . . + (-2)¹⁰³ - \(\text{[}\)(-2) +(-2)³ + (-2)⁵ + . . . + (-2)¹⁰¹ \(\text{]}\)

          3A=(-2)¹⁰³ + 2

Vậy A= \(\frac{-2^{103}+2}{3}\)

1) This is the first time he went abroad.=>

He hasn't gone abroad before. 

2) She started driving 1 month ago.

=> She has driven for 1 month.

3) We began eating when it started to rain.

=> We have eaten since it started to rain.

4) I last had my hair cut when I left her.

=> I haven't cut my hair after I left her.

5) The last time she kissed me was 5 months ago.

=> She hasn't kissed me for 5 months.

6) It is a long time since we last met.

=> We haven't met for a long time.

7) When did you have it ?

=> How long have you had it?
8) This is the first time I had such a delicious meal .

=> I haven't had such a delicious meal before.

9) I haven't seen him for 8 days.

=> The last time I saw him 8 days ago.

10) I haven't taken a bath since Monday.

=> It is the last I took a bath on Monday

There are forty students in my class

My class has forty students

Hoa can speak English fluently. Her sister can , too

Hoa can speak English fluently and so does her sister.

Nobody is taller than Khang in my class

Khang is the tallest in my class.

His old school is smaller than his new one

His new school is bigger than his old one.

I usually walk to school every day

I usually go to school on foot everyday.

They will have a garden in the new house next week

There will be a garden in their house next week.

The dictionaries are thicker than the books

The books are thinner than the dictionaries

Vì phép chia có số chia là 5 => số dư lớn nhất là 4. ( vì số dư luôn bé hơn số chia)

Vậy số mà An nghĩ ra là : 4 x 5 + 4 = 24

Đáp số : 24

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