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16 tháng 8 2021

a) <=> 4sinxcosx -(2cos2x-1)=7sinx+2cosx-4

<=> 2cos2x+(2-4sinx)cosx+7sinx-5=0

- sinx=1 => 2cos2x-2cosx+2=0 

pt trên vn

16 tháng 8 2021

b) <=> 2sinxcosx-1+2sin2x+3sinx-cosx-1=0

<=> cos(2sinx-1)+2sin2x+3sinx-2=0

<=> cosx(2sinx-1)+(2sinx-1)(sinx+2)=0

<=> (2sinx-1)(cosx+sinx+2)=0

<=> sinx=1/2 hoặc cosx+sinx=-2(vn)

<=> x= \(\frac{\pi}{6}+k2\pi\) hoặc \(x=\frac{5\pi}{6}+k2\pi\left(k\in Z\right)\)

- Phép tịnh tiến là một phép dời hình.

- Phép đối xứng trục là một phép dời hình.

- Phép vị tự với tỉ số −1 là một phép dời hình.

- Phép quay là một phép dời hình.

Choose the best answer in each sentence below by circling it. 1. You are late. If you …… a few minutes earlier, you …… him.       A. came / would meet        B. had come / would have met          C. come / will meet            D. had come / would meet2. “Can I borrow your car for this evening?”“Sure, but Nora’s using it right now. If she …… it back in time, you’re welcome to borrow it.”     A. brings                B....
Đọc tiếp

Choose the best answer in each sentence below by circling it.

1. You are late. If you …… a few minutes earlier, you …… him. 

     A. came / would meet        B. had come / would have met    

     C. come / will meet            D. had come / would meet

2. “Can I borrow your car for this evening?”

“Sure, but Nora’s using it right now. If she …… it back in time, you’re welcome to borrow it.”

     A. brings                B. would bring                 C. will bring                       D. brought

3. We’re going to lose this game …… the team doesn’t start playing better soon.

A. if                             B. unless                      C. although                 D. whereas

4. If I …… somebody else, I’d like to be a film star.  

     A. could be                             B. would be           C. become       D. must be

5. If he had told me the truth, I …… him.     

     A. would have not punished                      B. would not have punished

     C. would not punish                                  D. will not punish

6. If they had not given me advice, I …… again.   

     A. would have failed                     B. would fail         C. would have been failed                        D. wouldn’t fail

7. …… immediately, I will call a policeman.

     A. Unless you leave           B. If you leave             C. If you didn’t leave                        D. Unless you left      

8. Bill …… more photographs if he …… more film.  

     A. would have taken / had had                  B. would have taken / had

     C. would take / has had                             D. would take / had had        

9. If there …… no floods last year, the crop …… better. 

     A. had been / would have been     B. were / would be  

     C. had / would have been               D. was / would have been

10. Had you told me that this was going to happen, I …… it.   

     A. would never have believed         B. don’t believe

    C. hadn’t believed                            D. can’t believe

11. If someone …… into the store, smile and say, “May I help you?”

     A. comes                B. came                       C. come                       D. could come

12. If I had a chance to do creative work, I …… happy working in an office.

     A. would be                       B. will be                     C. would have             D. will feel

13. If they …… soon, I’m not going to wait.  

     A. don’t come        B. won’t come                   C. hadn’t come        D. didn’t come

14. If I …… hungry, I …… something. But I am not hungry now.  

     A were / would eat                         B. had been / would have eaten        

     C. had been / would eat      D. were / would have eaten

15. You won’t pass the examination …… you study more.    

     A. unless         B. as           C. if                 D. whether

16. I’m playing tennis tomorrow …… it’s raining.    

     A. unless              B. if                   C. as long as    D. provided

17. Tell him to ring me if you …… him.   

     A. see                     B. saw             C. have seen                D. had seen

18. Unless she ……, she’ll be late.    

     A. hurries               B. didn’t hurry                        C. hurried                    D. doesn’t hurry

19. Would George be angry if I …… his bicycle without asking?  

     A. took      B. take             C. had taken    D. would take

20. I …… you a postcard while I was on holiday if I …… your address.

A. would have sent / had had       B. would have sent / had      

C. would send / had                      D. would send / had had

21.  …… still my friend if I were put in prison?  

     A. Would you be            B. Will you be           C. Would you        D. Would you are

22.  If anybody …… any question, please ask me after class.  

     A. has         B. have                C. don’t have                      D. doesn’t have

23.  If I weren’t working for an accounting firm, I …… in a bank.

A. would be working        B. will work         C. have worked         D. work

24. He said, “…… watch TV all the evening if you wish.”  

     A. You may           B. You have to              C. You need to             D. You should

25. If he ……, please tell me.    

     A. comes                B. won’t come                        C. will come                D. come

2
14 tháng 8 2021

Theo em nghĩ thì là C vì You thì ko thể dùng had đc.

14 tháng 8 2021

sao nhiều thế. Ai mà trả lời nổi