1 A

2 D

3 B

4 D

5 A

6 D

7 C

8 A

9 C

10 B

11 D

IV

12 went

13 is playing

14 closing

15 don't drink

16 would visit

17 B

18 D

19 B

20 D

21 cook

22 it

23 his

24 On

25 him

26 because

27 B

28 D

29 C

30 B

31 A

VIII

1 Janet isn't interested in watching sports on TV

2 I Think you should go to school by bike

3 Lake Baikal is the deepest lake in the world

4 He doesn't have enough time to complete the test

5 The last time he visited HLB is 5 years ago

IX 

37 In dry season there is alway a lack of water

38 Yesterday he was so tired that he didn't finish his work

39 There are 10 fingers and two arms on the body

40 What kind of TV programme do you like to watch the most when you were small?

Đề bài sai nhé, từ giả thiết chỉ xác định được \(x+y=0\Rightarrow y=-x\)

\(\Rightarrow A=4x^2-x^2+x^2+15=4x^2+15\) ko rút gọn được

Giải phương trình ak

x=4- căn 6;x=căn 6 +4

Giải phương trình đó bạn . giúp mình giải cụ thể đi 

ta có 3S=\(3\left(3+3^2+3^3+...+3^{2010}\right)\)

3S=\(3^2+3^3+3^4+3^5+...+3^{2011}\)

2S=3S-S=\(3^2+3^3+3^4+3^5+...+3^{2011}\)-\(-\)\(3+3^2+3^3+...+3^{2010}\)

2S=\(3^{2011}-3\)

=> 2S+3 =3x

=>\(3^{2011}-3+3=3x\)

=>x=\(3^{2010}\)