$x^{2}-2(m-1)x-4m=0$
Ta có: $\Delta'=b'^2-ac\\\hspace{2cm}=[-(m-1)]^2]-1.(-4m)\\\hspace{2cm}=m^2-2m+1+4m\\\hspace{2cm}=m^2+2m+1\\\hspace{2cm}=(m+1)^2$
Để phương trình có 2 nghiệm phân biệt
$\to \Delta'>0$
$\to (m+1)^2>0$
$\to m\ne-1$ thoả mãn đề bài
Nêu kế hoạch đánh chiếm Bắc Kì lần thứ nhất (1873) của thực dân Pháp
I. Tìm lỗi sai và sửa lại. 1.I live in apartment on Nguyen Trai Street. _______ 2.what do you doing tomorrow?. ________ 3.there is some new furnitures in the living room _______ 4.my mother have short curly hair and big blue eyes _____ 5 would you like going to the movies tonight? ______ II. Lối 1. Where does your brother live? a.oh I’d love to! 2. What does he look like? b. He’s a bit boring. He really doesn’t like anything. 3. What’s he like? c .No , thanks. I’m Full 4.What does he like? d . Orange juice , please. 5. Would you like something to eat?e. He’s shortish with dart brown hair. 6. Would you like to have dinner with me on Friday ? f. Yes , sure 7. Can’t you pass me that book, please? g. In Da Nang 8 . What would you like to drink? h. He’s friendly and easy - going
Tính giá trị biểu thức: B=-5/7+2/-7+4/9+4/9 C=(3-3/4+2/3)-(2+4/3-3/2)-(1-7/3-9/2)
Chứng minh ngành công nghiệp dệt may là ngành có vai trò chủ đạo trong ngành công nghiệp sản xuất hàng tiêu dùng
21) When he ____, we ____ dinner. A. arrived/having B. arrived/were having C. was arriving/had D. had arrived/had 22) While they ____ chess, we ____ the shopping. A. playing/doing B. were playing/doing C. played/did D. were playing/were doing 23) They ____ football when the lights in the stadium ____ out. A. were playing/went B. played/was going C. were playing/ was going D. playing/went 24) While George and John ____ their room, she ____ the ironing. A. cleaning/doing B. were cleaning/was doing C. were cleaning/doing D. cleaning/was doing 25) Today is Thursday and she ____ late twice this week. She ____ late yesterday and on Monday. A. is/was B. has been/is C. has been/was D. has been/had been 26) He ____ in the same house since 1975. A. has lived B. is living C. lived D. had lived 27) We ____ him since he ____ married. A. didn’t see/got B. haven’t seen/got C. don’t/get D. hadn’t seen/got 28) It ____ for two hours and the ground is too wet to play tennis. A. is raining B. had rained C. has rained D. was raining 29) He ____ to HCMC last year and I ____ him since then. A. moved/didn’t see B. moves/haven’t seen C. moved/haven’t seen D. moved/hadn’t seen 30) We ____ what to do with the money yet. A. not decide B. didn’t decide C. haven’t decided D. hadn’t decided 31) My father ____ as a teacher for thirty years. A. works B. is working C. worked D. has worked 32) He ____ to New York three times this year. A. had been B. was C. has been D. is 33) I ____ how to dance when I ____ six years old. A. don’t know / was B. didn’t know / am C. didn’t know / was D. haven’t known/was 34) Last month my brother ____ me his photos. He ____ me his photos every year. A. sends/sent B. sent/sends C. sent/sent D. sends/sends 35) Nam is a careful driver but yesterday he ____ carelessly. A. drove B. had driven C. drives D. was driving 36) Do you like swimming, Ba? – I ____ when I was a child but not now. A. do B. did C. have done D. had done 37) I ____ her at the school gate yesterday. A. met B. meet C. had met D. am meeting 38) She ____ English when she was six years old. A. learned B. has learned C. is learning D. had learned 39) I don’t remember where and when I ____ her. A. meet B. had met C. met D. have met 40) They ____ to know each other for more than ten years. A. get B. got C. have got D. had got 41) ____ you ____ that film yet? A. Do/see B. Have/seen C. Did/see D. Had/seen 42) I ____ the film with my friends last week. A. watched B. watch C. have watched D. had watched 43) He ____ up at five every morning. A. is getting B. got C. gets D. was getting 44) ____ she ____ in Hue at the moment? A. Does/live B. Is/living C. Did/live D. Was/living 45) He usually __ her at weekend but now he __ in bed because of his severe illness. A. visits/stays B. visits/staying C. visited/stays D. visits/is staying 46) Don’t make noise, children! Parents ____. A. sleep B. are sleeping C. were sleeping D. slept 47) Why ____ you always ____ so much noise in the house? I don’t like that. A. do/make B. did/make C. are/making D. were/making 48) What ____ he ____ before you came? A. does/do B. had/do C. had/done D. has/done 49) While mum was watching TV, I ____ my homework. A. am doing B. was doing C. had done D. has done 50) At this time yesterday I ____ to music. A. listened B. had listened C. was listening D. am listening 51) What ____ he ____ at 4 P.m. last Sunday? A. did/do B. was/do C. had/done D. was/ doing 52) When I ____ a little girl, I used to climb trees and go swimming in the river with my friends. A. am B. was C. have been D. had been 53) Last year he came here and ____ me to marry him but I ____ too young to get married. A. asked/ was B. asks/am C. had asked/was D. has asked/am 54) How long ____ you ____ novels? A. have/write B. do/write C. have written D. are/writing 55) ____ you sometimes ____ out with friends? A. Are/going B. Do/ go C. Have/gone D. Did/go 56) I ____ a lot of badminton recently. A. play B. have played C. am playing D. was playing 57) When I ____ home, everyone ____ TV. A. got/watch B. got/watching C. get/was watch D. got/ was watching 58) We ____ your mother for ages. A. don’t see B. haven’t seen C. didn’t see D. hadn’t seen 59) London ____ a lot since we first ____ to live here. A. changed/came B. has changed/ came C. had changed/ came D. has changed/ come 60) How many times ____ you ____ this film? – The first time. A. have/ seen B. did/see C. do/see D. had/seen mình cần gấp nhé
Câu 7: Viết toạ độ địa lý của các điểm A, B biết : - A có vĩ độ là 20 0 Nam, kinh độ là 400 Đông. A - B có kinh độ là 250 Tây, vĩ độ là 100 Bắc
giúp mình vs ạ mình cảm ơi trước
Phản ứng hóa học có sơ đồ sau: C2 H6O + O2 → CO2 + 3H2 O. Tổng hệ số tối giản sau khi cân bằng của các chất là Phản ứng hóa học có sơ đồ sau: CH4 + O2 → CO2 + H2O Tổng hệ số tối giản sau khi cân bằng của các chất là Phản ứng hóa học có sơ đồ sau: C2H5OH + 3O2 → 2CO2 + 3H2O Tổng hệ số tối giản sau khi cân bằng của các chất là
Một hình chữ nhật có diện tích là 1176 cm vuông. Nếu giảm chiều rộng đi 4 cm thì diện tích hình chữ nhật là 1080 cm vuông. Tính chiều dài và chiều rộng của hình chữ nhật đó.
Find the word which has a different sound in the underlined part. hear fear dear wear near appear bear idea here there series sphere aerobics air chair marry prepare carry share fair
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