$\begin{array}{l} W = \left( {2x - 4} \right)\left( {4{x^2} + 8x + 16} \right) - {\left( {x - 2y} \right)^3} + {\left( {y - 1} \right)^3}\\ W = 8{x^3} - 64 - \left( {{x^3} - 6{x^2}y + 12x{y^2} - 8{y^3}} \right) + \left( {{y^3} - 3{y^2} + 3y - 1} \right)\\ W = 7{x^3} + 6{x^2}y - 12x{y^3} + 9{y^3} - 3{y^2} + 3y - 65\\ W = 7.{\left( { - 1} \right)^3} + 6.{\left( { - 1} \right)^2}.\dfrac{1}{2} - 12\left( { - 1} \right).{\left( {\dfrac{1}{2}} \right)^3} + 9{\left( {\dfrac{1}{2}} \right)^3} - 3{\left( {\dfrac{1}{2}} \right)^3} + 3\left( {\dfrac{1}{2}} \right) - 65\\ W = \dfrac{{ - 525}}{8} \end{array}$
Đáp án + giải thích các bước giải:
`W=(2x-4)(4x^2+8x+16)-(x-2y)^2+(y-1)^3`
`=(2x-4)([(2x)^2+2x.4+4^2]-x^2+4xy-4y^2+y^3-3y^2+3y-1`
`=8x^3-64-x^2+4xy-4y^2+y^3-3y^2+3y-1`
`=8x^3-x^2+4xy-4y^2-3y^2+y^3+3y-65`
`=8x^3-x^2+4xy-7y^2+y^3+3y-65`
`=8.(-1)^3-(-1)^2+4(-1). 1/2-7. (1/2)^2+(1/2)^3+3.1/2-65`
`=-8-1-2-7/4+1/8+3/2-65`
`=-609/8`
Câu 1: Tính pH của các dung dịch sau: a) dung dịch HCI 0,2 M b) dung dịch Ca(OH), 0,4M Câu 2 : Đốt cháy hoàn toàn 18,5 gam hợp chất hữu cơ (A) thu được 16,8 lít CO2 (đktc) và 13,5 gam H,O. Ti khối của A so với H, là 37. Xác định công thức phân tử và công thức đơn giản nhất của A. (Cho biết C= 12, H = 1; 0 =16, N= 14) Câu 3 :Hòa tan hết 6,95 gam hỗn hợp Al và Fe vào dung dịch HNO; đặc, nóng (dư) thu được 10,08 lít khí NO2 duy nhất (điều kiện tiêu chuẩn). Tính khối lượng mỗi kim loại trong hỗn hợp ban đầu giúp em với ạ em cảm ơn
Lớp 6A có 45 học sinh . Số học sinh giỏi chiếm 2/9 số học sinh cả lớp , số học sinh khá chiếm 4/15 số học sinh cả lớp , số học sinh trung bình chiếm 40% số học sinh cả lớp, số học sinh còn lại là học sinh yếu . tính số học sinh giỏi , khá , trung bình,yếu của lớp 6A
rút gọn và tính giá trị của các biểu thức sau
Ai giúp mình với em cảm ơn trc ạ
viết lại câu (có cấu trúc hoặc công thức đi kèm càng tốt) y/c lm đúng 86. There was never any answer when we rang. => Every…………………………………………………………………………………………… 87. That’s an insulting name to use for him. => Don’t call…………………………………………………………………………………….. 88. John asked if it was the blue one or the green she wanted. => Which………………………………………………………………………………………….. 89. She liked Paris very little, and Rome less. => She thought Rome…………………………………………………………………………. 90. I can meet you if you arrive before eleven. => So……………………………………………………………………………………………….. 91. They will catch all the prisoners again by tonight. => All the prisoners……………………………………………………………………………. 92. I’ve warned you not go to near that dog. => I’ve warned you about…………………………………………………………………… 93. No, please don’t tell him. => I’d rather………………………………………………………………………………………. 94. Why don’t ask her yourself? => I suggest……………………………………………………………………………………….
Giúp mình với mình đang cần gấp
Bài 2. Bài tập hiện tại đơn, hiện tại tiếp diễn 1. Where's John? He _______________(listen) to a new CD in his room. 2. Don't forget to take your umbrella with you to London. You know it always ________ (rain) in England. 3. Jean ________(work) hard all day but she ________(not work) at the moment. 4. Look! That boy ________ (run) after the bus. He________(want) to catch it. 5. He ________(speak) German so well because he ________(come) from Germany. 6. Shh! The boss ________(come). We __________(meet) him in an hour and nothing is ready! 7. ________you usually ________(go) away for Christmas or________ you ________(stay) at home? 8. She ____________(hold) some roses. They__________(smell) lovely. 9. Oh no! Look! It ____________(snow) again. It always________________(snow) in this country. 10. Mary ___________ (swim) very well, but she ______________(not run) very fast. 11. ________ you ________(enjoy) this party? Yes, I __________(have) a great time! 12. Sorry I can't help you. I _____________(not know) where she keeps her files. 13. What ________you________(do) next Saturday? Nothing special. I ___________ (stay) at home. 14. I ___________ (think) your new hat ____________(look) nice on you. 15. I ________ (live) with my parents but right now I ________(stay) with some friends for a few days. 16. I can't talk on the phone now. I _____________ (drive) home. 17. Where are the children? They _____________ (lie) on the beach over there. 18. You never ________(listen) to a word I say! You ________always ________ (listen) to that mp3 player! 19. He ___________ (not understand) what you ____________ (talk) about. He's foreign. 20. How much ___________your suitcase ___________(weigh)? It ____________ (look) really heavy. viết đáp án là được ạ
IV.Give the correct form of the word in brackets 1.We are going to.......our school next year (large) 2.She always listens................to what she is told (attention) 3.There was loud..............as the clown fell off the ladder (laugh) 4.The alpine..............is very dramatic (land) 5.This matter is very...................Don't discuss it outside the office (confidence) 6.Such blocks are frequently left.................and, as prices go up, they increase in value (occupy) 7.Is there any difference between egoism and.................? (self) 8.The speaker showed his nervousness by constantly.............his tie (straight) 9.If you behave with this sort of................to your other customers, i don't think you'll remain in bussiness long (polite) 10.The manager handed in his...............after being accused of dishonesty (resign) III.There is one mistake in each sentence.Find the mistake and corect it 1.We'd better not say anything,did we? 2.If you don't like that program, you can switch always over to a different channel 3.He stepped onto the scales and saw that he was the same weight like his friend 4.The doctors have to go to school for many years to complete their education 5.That new medicine will not be ready availableuntil next year 6.Did the teacher mind us whispering in the back of the room? 7.Long is going to decide about his future course of study 8.He appeared nervously as he began to take the exam 9.My neighbor has a lovely cat, but it meowing bothers me at night 10.She could not help noticing the man to cry like a child (giúp mình vớii mình sẽ cho 5 sao và cảm ơn ạ)
Choose the letter A, B, C or D to indicate the correct answer to each of the following question. Question. I enjoy watching action films _____________ some of them are rather violent. A. in spite of B. although C. despite D. however Question. Cutting down on what you throw away is good ___________ the environment. A. at B. for C. of D. with Question. Solar panels _____________ on the roofs of houses and other buildings. A. will put B. will be put C. will be putting D. will putting Question. I think nuclear power is not only expensive but also _____________ to our environment. A. danger B. dangerous C. safe D. limited Choose letter A, B, C or D to indicate the sentence that is closest in meaning to the original sentence in each of the following questions. Question. People won’t burn fossil fuels for energy in the future. A. Fossil fuels won’t be burned for energy in the future. B. Fossil fuels won’t be burn for energy in the future. C. Energy won’t be burned fossil fuels in the future. D. Fossil fuels won’t be burning for energy in the future. Question. My father usually went fishing two years ago but he doesn’t now. A. My father used to going fishing two years ago. B. My father used to go fishing two years ago. C. My father didn’t use to going fishing two years ago. D. My father used to went fishing two years ago. Question. It/ important/ us/ learn/ use/ roads properly/ safely. A. It is important for us to learn to use the roads properly and safely. B. It is important to us to learn use the roads properly and safely. C. It is important for us to learn use the roads properly and safely. D. It is important to us to learn to use the roads properly and safely. Question. Despite/ heavy/ rain, I/ went/ school/ on time. A. Despite of the heavy rain, I went to school on time. B. Despite the heavy rain, I went to school on time. C. Despite to the heavy rain, I went to school on time. D. Despite heavy rain, I went to school on time. Question. This film was made twenty- five years ago. Many people have enjoyed seeing it. A. In spite of this film was made twenty - five years ago, many people have enjoyed seeing it. B. Although this film was made twenty - five years ago but many people have enjoyed seeing it. C. Although this film was made twenty - five years ago, many people have enjoyed seeing it. D. This film was made twenty five - years ago despite many people have enjoyed seeing it. Question. It takes him 30 minutes to do morning exercise every day. A. He spends 30 minutes doing morning exercise every day. B. He spends 30 minutes to do morning exercise every day. C. He spends 30 minutes to doing morning exercise every day. D. He spends for 30 minutes doing morning exercise every day. Giúp tôi vs tôi cần gấp ạ
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