\(\frac{3^2}{2\cdot11}+\frac{3^2}{11\cdot14}+...+\frac{3^2}{197\cdot200}=\frac{3^2}{2\cdot11}+\left(\frac{3^2}{11\cdot14}+...+\frac{3^2}{197\cdot200}\right)\)

\(=\frac{9}{22}+3\left(\frac{3}{11\cdot14}+...+\frac{3}{197\cdot200}\right)=\frac{9}{22}+3\left(\frac{1}{11}-\frac{1}{14}+...+\frac{1}{197}-\frac{1}{200}\right)\)

\(=\frac{9}{22}+3\left(\frac{1}{11}-\frac{1}{200}\right)=\frac{9}{22}+3\left(\frac{200}{2200}-\frac{11}{2200}\right)=\frac{9}{22}+3\cdot\frac{189}{2200}\)

\(=3\cdot\left(\frac{3}{22}+\frac{189}{2200}\right)=3\cdot\left(\frac{300}{2200}+\frac{189}{2200}\right)=3\cdot\frac{489}{2200}=\frac{1467}{2200}\)

\(\left(\dfrac{-1}{3}\right)^4=\dfrac{\left(-1\right)^4}{3^4}=\dfrac{1}{81}\)

\(\left(-2\dfrac{1}{4}\right)^3=\left(-2\right)^3\cdot\left(\dfrac{1}{4}\right)^3=-8\cdot\dfrac{1}{64}=-0,125\)

\(\left(-0,2\right)^2=0,04\)

\(\left(-5,3\right)^0=1\)

1. Yes. I'd like a cup of coffee, please.

=> Would you like something to drink?

2. A bowl of chicken noodle is 4,000 dong.

=> How much is a bowl of chicken noodle?

3.Yes. There is some fruit in the fridge.

=> Is there any fruit in the fridge?

4. I'm cold and I'm hungry

=> How do you feel?

5. She has big brown eyes.

=> What does she look like?

6. My father goes jogging three times a week.

=> How often does your father go jogging?

7. I read and listen to music.

=> What do you do?

8. We are playing badminton, now.

=> What are you doing now?

9.Two hundred grams, please.

=> How much?

10. He is a weight lifter.

=> What's his job?

13. They won't go shopping if they don't have (not/have) much money

14. They don't walk (not / walk ) at night

15. We don't understand ( not / understand ) what they are saying

16. They won't go shopping if they don't have (not / have) much money

17. He doesn't rest (not / rest) after lunch time

Đặt A=1.2.3+2.3.4+...+98.99.100

=>4.A=1.2.3.4+2.3.4.4+...+98.99.100.4

=>4.A=1.2.3.(4-0)+2.3.4.(5-1)+...+98.99.100.(101-97)

=>4.A=1.2.3.4-0.1.2.3+2.3.4.5-1.2.3.4+...+98.99.100.101-97.98.99.100

=>4.A=98.99.100.101

=>4.A=97990200

=>A=24497550

Vậy 1.2.3+2.3.4+...+98.99.100=24497550

1.- Where are the children?

-In the living room.

-What are they doing? Are they watching TV?

-No, they are playing a game.

2.-You look tired. Do you feel hungry? Would you like some bread?

3. - I think it is a pity you don't take more exercise.You are going to get fat.

1. My class visited Hung King's Temple last week.

-> Hung King's Temple was visited by my class last week.

2. Listening to music is more interesting than watching TV.

-> I like listening to music more than watching TV.

(3n+14) CHIA HẾT CHO (N+2) =>3(n+2)+8 chia hết cho n+2

Mà 3(n+2) chia hết cho n+2=> 8 chia hết cho n+2

=> n+2 thuộc Ư(8)=(1;2;4;8)

 Mà n là số tự nhiên=> n+2 thuộc(2;4;8)

=> n thuộc(0;2;6)

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