Cho ∆ABC, kẻ AH vuông góc BC và\(\widehat{ }\)góc BAH=2CAH. Tính góc B và C, biết góc A=72°

Bài 1: Tìm a,b,c:

a, a.b=35 ;b.c=45 ;c.a=34

b, a.(a+b+c)= -12

b.(a+b+c)= 18

c.(a+b+c)= 30

c, a.b=c; b.c= 4a; a.c= 9b

1. Cho:

C = 1/3+1/3^2+1/3^3+...+1/3^99

Chứng minh C<1/2

2. Cho: A=3/1^2×2^2+5/2^2×3^2+7/3^2×4^2+...+19/9^2×10^2

Giúp mình với chiều nay 2h30 🕝 e ik hc r

Tìm x,y

a, 2^x+1 x 3^y = 12^x

b, 10^x : 5^y = 20^y

Vẽ đường thẳng xy//zt. Đường thẳng c cắt đường thẳng xy tại A, cắt zt tại B. Vẽ Ah là tia phân giác góc xạ, Bk là tia phân giác góc ABt

a) Vẽ hình.

b) Chứng tỏ Ah//Bk

( giúp mk vs mai nộp rồi )

Bài 1: Tìm giá trị nhỏ nhất

A = ( X+3 )² - 15

B = ( x-1 )² + 7

Bài 2: Tìm giá trị lớn nhất:

A = - ( x-3 )² + 2

B = - ( x+7 )² - 1

m.n giúp e vs mai e nộp r

Change these sentences into reported speech:

1. Hong told Hoa, '' I want to know what was Mom doing at that time''

2. Simon is saying to Susan, '' Would you and Maline like to come to my party?''

3. '' I have left my key a home. What time it is now?'' he asked me.

4. '' I am going shopping. Can I get you anything?'' she said to Tan.

5. '' Someone is coming'', he said. '' Get behind the screen.''

6. '' Please, please don't drink too much! Remember that you'll have to drive home''

7. Daniel said, '' Is there a café nearby?'' and Tom said, ''No''

8. Hang said: '' Why doesn't Ha buy them this pictures as a wedding present?''

9. '' I can't work at all ! My typewriter isn't working properly,'' she said

10. '' I think you should try to be more punctual,'' she said to Ha

11. '' You can't park here'', the policeman said.

12. '' Have you worked before?'' she said to him

13. '' Can you worked on Saturday before?'' she said to him

14. '' May I open the window?'' she asked

15. '' Would it be alright if had the day off?'' she said to her boss

16. '' May I borrow your tennis racket?'' she asked him

17. '' Are you coming to the party tonight, Ha?'' she asked

18. '' Do you know where my tennis racquet is, Mum?'' she asked her Mum

19. '' Was Ha at work yesterday?'' she asked her secrectery

20. '' Did you read the article about Prince Diana?'' she asked him

21. '' Where do you live?'' she said to him

22. '' Why do you want the job?'' she sai to him

23. '' How did you hear about it?'' she said to him