Câu 1, 2 như hình.
Câu 3:
$f(x)=3x^2+2(2m-1)x+m+4>0 \forall x$
$\Rightarrow \Delta'<0$
$\Delta'=(2m-1)^2-3(m+4)$
$=4m^2-4m+1-3m-12$
$=4m^2-7m-11$
$=(m+1)(4m-11)<0$
$\Leftrightarrow -1<m<\dfrac{11}{4}$
Giải thích các bước giải:
Để hàm số f(x) luôn dương ∀ x∈R ⇔ f(x) > 0
⇔ Δ' < 0
⇔ (2m-1)² - 3(m+4) < 0
⇔ 4m² -7m - 11 < 0
⇔ -1<m<11/4
Cho 5,4(g) hỗn hợp 2 kim loại( hóa trị II III ) tác dụng H2SO4(loãng,dư) thu được 10,08(l) khí (đktc).Biết tỉ lệ nguyên tử khối khối lượng kim loại hóa trị II và III là 1:3.Còn tirleej số nguyên tử 3:1 .Tìm tên 2 kim loại đó
Giải hệ phương trình sau: 3x+2=-y -x+4=y
help me pls ~(´ε` ) , nhanh nhé ><
các bn lam giúp mk vs mk cần gấp
Tìm x a,5x-8=-23 b, 5.(x-3)+6=x-(21-2x)
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Vẽ cho mình SCP 999(cục slam màu cam siu cute)nha!! Full màu Tradi hay digi chấp nhận hết Mới xem ẻm xong thía ẻm cute quá khum chịu đc ước j mik có 1 ẻm Nếu có bonus thì là đậu mầm nha Ctlhn dành cho ng có bonus
1. Do you go to school on ________ or by bike A. toe B. foot C. knee D. leg 2. Mr Hung is traveling to Ha Noi ________ bus. A. in B. on C. by D. of 3. How ________ is a sandwich? -It’s two thousand dong. A. many B. much C. old D. long 4. Mom: Would you ________ noodles? Lan: Yes, please. A. want B. like C. has D. have 5. She ________ doing aerobics now. A. are B. does C. is D. has 6. My students sometimes ________ their kites. A. play B. fly C. flys D. run 7. Minh often goes ________ in the mountains with Tan and Nga. A. walking B. run C. walk D. walks 8. Tan: What ________ going to the movie theater? Nam: Yes. Good idea. A. on B. in C. about D. to 9. How ________ are they going to stay there? - For 3 days. A. many B. much C. old D. long 10. Let’s ________ camping this weekend. A. going B. goes C. go D. to go 11. What’s the weather ________ in the Fall? A. hot B. cold C. like D. want 12. Teacher: ________ color is your Mom’s hair? Thu: It’s black. A. Where B. How C. When D. What 13. Van: Are there ________ tomatoes in that basket? Mai: Yes, there are. A. a B. an C. any D. some 14. Ba: ________ there any fruit for dinner, Mom? Mom: Yes, there are some bananas and apples. A. Are B. Is C. Have D. Has 15. How ________ homework do you have every day? A. much B. many C. old D. there 16.They_________the bus yesterday. A. don’t catch B. weren’t catch C. didn’t catch D. not catch 17. My sister_________home last night. A. comes B. come C. came D. was come 18. My father_________tired when I _________ home. A. was – got B. is – get C. was – getted D. were – got 19. What_________you_________two days ago? A. do – do B. did – did C. do – did D. did – do 20.Where_________your family_________on the summer holiday last year? A. do – go B. does – go C.did – go D. did – went 21. We_________David in town a few days ago. A. did see B. was saw C. did saw D. saw 22. It was cold, so I_________ the window. A. shut B.was shut C. am shut D.shutted 23. I_________to the cinema three times last week. A.was go B. went C. did go D.goed 24.What_________you_________last weekend? A.were/do B.did/did C.did/do D.do/did 25.The police_________on my way home last night. A. was stop B.stopped C.stops D.stopping 26. The film wasn’t very good. I_________ it very much. A.ẹnjoyed B.wasn’t enjoy C.didn’t ẹnjoyed D. didn’t enjoy 27.The bed was very uncomfortable. I_________sleep very well. A.didn’t B.did C.wasn’t D.not 28. The window was opened and a bird_________into the room. A.fly B. flew C. was flew D.did fly 29. I_________a lot of money yesterday. I_________an expensive dress. A.spend/buy B.spent/buy C.spent/bought D.was spent/bought.
Giusp iemm bài hình vs ạ:(( Pls:33
I. CHOOSE THE BEST ANSWER. 1. Linda used to _______ morning exercise when she got up early. A. did B. does C. doing D. do 2. My mum _______ the bus to work every day, but I cycle. A. catches B. drives C. goes D. runs 3. Did you _______ play football when you were at high school? A. are used to B. used to C. use to D. use 4. When I was at primary school, my father _______ me to school every day. A. takes B. is taking C. used to take D. is used to taking 5. There _______ a stadium in the town but now there isn’t. A. use to be B. was used to C. is used to D. used to be 6. He _______ a packet a day but he stopped two years ago. A. used to smoke B. uses to smoke C. used to smoking D. is used to smoking 7. She didn’t use to _______ in the hospital. A. work B. working C. to work D. worked 8. Did you _______ to the cinema when you lived in London? A. used to go B. were used to go C. use to go D. were used to going 9. When my brother was a boy, he _______ fishing. A. was used to going B. used to go C. used to going D. is used to going 10. . My mother _______ to work but now she takes the bus. A. use to walk B. used to walk C. was used to talk D. was used to walking
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