Đáp án:
1/2
Giải thích các bước giải:
x(x+y)-x(y-X) tại x=-1/2va y=3
Thay x=-1/2 và y=3 vào x(x+y)-x(y-X)
= (-1/2)(-1/2+3) - (-1/2){3-(-1/2)}
= (-1/2).5/2 - (-1/2).7/2
= (-5/4) - (-7/4)
= 1/2
\[x(x+y)-x(y-x)=x^2+xy-xy+x^2=2x^2\]
Thay $x=\dfrac{-1}{2}$
\[\to x(x+y)-x(y-x)=2x^2=\dfrac{1}{2}\]
Nêu cảm xúc của em về người bà (7 đến 10 dong) qua bài thơ tiếng gà trưa
Đốt cháy 7,2g ankan A thu 0.6 mol H2O .Tìm CTPT của ankan
giup
26. If I had taken that English course, I ………..much progress. a. had made b. would have made c. made d. would make. 27. If I were in your place, I ……….a trip to England. a. will make b. had made c. made. d. would make. 28. If I ………….. you , I’d save some of your lottery winning. a. be b. were c. am d. was 29. If the car ……….. larger, we would have bought it. a. had been b. have been c. has been d. been 30. If I had enough money, I ……… abroad to improve my English. a. will go b. should go c. would go d. should have go to 31. If it …….. convenient, let’s go out for a drink tonight. a. be b. was c. were d. is 32. If you ……. time, please write to me. a. have b. have had c. had d. has 33. If you had the chance, ………… you go finishing? a. did b. would c. may d. do 34. Trees won’t grow ……….. there is enough water. a. if b. when c. unless d. as 35. If you ………. to my advice in the first place, you wouldn’t be in this mess right now. a. listen b. had listened c. will listen d. listened 36. I wish I …….. you some money for your rent, but I’m broke myself. a. can lend b. could lend c. would lend d. will lend 37. If someone ……… into the store, smile and say, “ May I help you?” a. comes b. came c. would come d. could lend 38. If you stay up late the previous night, you ………. sleepy the next morning. a. feel b. to feel c. feels d. will feel 39. If Peter ………., Sarah will be sad because she wants to meet him very much a. comes b. do not come c. does not come d. will come 40. If his teeth still …….., he will have to go to the dentist’s again. a. hurt b. hurts c. to hurt c. will hurt 41. If you…………Tom , tell him I have a message for him. a. will meet b. would meet c. meet d. met 42. If you …………too hot during the night , turn down the central heating. a. will feel b. felt c. feel d. feels. 43. If you …………with your dictionary, I ‘d like to borrow it. a. finish b. finished c. will finish d. are finishing. 44. If I lived nearer the centre , I …………always late. a. wouldn’t be b. can be c. won’t be d. will be. 45. What would Lan do if she …………..the Miss world. a. would be b. were c. will be d. is. 46. If I ………….her , I would have said “ hello” a. has seen b. have seen c. saw d. had seen. 47. If she had read the passage more slowly , the candidate……………………. a. understood. B. would have understood c. will understood d. would understand. 48. If it……………, they will not go out. a. rains b. rained c. rain d. raining. 49. Jame will not complete the work if she is …………..rarely enough. a. tell b. telling c. tells d. told. 50. Betty will not go to the party unless John ……………….too. a. go b. went c. going d. goes
Cho các lọ mất nhãn đựng các dung dịch ko màu: Ba(NO3)2; Na2CO3; KCl; Na2SO4 Chỉ dùng thêm 1 thuốc thử, hãy nhận biết các dung dịch trên.
1.if i….a lot of money now, I …………..a new car. a. have /will buy b. have / would buy c. had/ will buy d. had/ would buy. 2. If I ……………you, I …………….do that. a. am/ will b. were /would c. were/ will d. had been/ would. 3. If I were offered the job, I think I ………. it. a. take b. will take c. would take d. would have taken. 4. I would be very surprised if he…………….. a. refuses b. refused c. had refused d. would refuse. 5. Many people would be out of work if that factory………..down. a. closes b. had closed c. closed d. would close. 6. If she sold her car, she ………… much money. a. gets b. would get c. will get d. would have got. 7. They would be disappointed if we……………. a. hadn’t come b. wouldn’t come c. don’t come d. didn’t come. 8. Would John be angry if I ……. ……his bicycle without asking? a. take b. took c. had taken d. would take. 9. She ……….terrible upset if I lost this ring. a. will be b. would be c. were d. had been. 10. If someone…………in here with a gun, I would be very frightened. a. would walk b. walks c. had walked d. walked. 11. What would happen if you ……………..to work tomorrow? a. don’t go b. didn’t go c. won’t go d. wouldn’t go. 12. We ‘ll get wet if we ………….out. a. go b. did go c. went d. had gone. 13. If I go shopping, I ………some food. a. buy b. will buy c. would buy d. would have bought. 14. If I find it, I ………you. a. will tell b. would tell c. had told d. told. 15. What would you do if you……………a million dollars? a. would win b. win c. had won d. won. 16. They ‘d be hurt if I ………………. a. don’t go b. didn’t go c. hadn’t gone d. wouldn’t go. 17. If we took the 6: 30 train, we…………too early. a. would have arrived b. arrived c. will arrived d. would arrive. 18. If I had known you were in hospital, I …………to see you. a. will go b. would go c. went d. would have gone. 19. If I …………., I would have said hello. a. had seen b. see c. saw d. would see. 20. I…………..out if I hadn’t been so tired. a. will go b. went c. would have gone d. would go. 21. If I ………..a camera, I would have taken some pictures. a. have b. had c. would have d. had had. 22. You won’t pass the examination……………you study more. a. as long as b. unless c. if d. whether. 23. If only I …………you wanted to invest money in business. a. had known b. knew c. have known d. know. 24. If I were to leave my country , I ……………disappointed. a. probably be b. would have been c. will be d. would be. 25. If he hadn’t wasted too much time, he…………….in his examination. a. would fail b. wouldn’t fail c. wouldn’t have failed. d. won’t fail.
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