Đáp án+Giải thích các bước giải:
`2x^2-3x+1`
`=2.(x^2-(3)/(2)x+(1)/(2))`
`=2.[x^2-2.(3)/(4).x+(3/4)^2-(3/4)^2+1/2]`
`=2.[(x-3/4)^2-(1)/(16)]`
`=2.(x-3/4)^2-1/8`
Vì `(x-3/4)^2≥0∀x∈RR=>2.(x-3/4)^2≥0∀x∈RR`
`=>2(x-3/4)^2-1/8≥-(1)/(8)∀x∈RR`
`=>2x^2-3x+1≥-(1)/(8)∀x∈RR`
Dấu `=` xảy ra:
`⇔x-3/4=0<=>x=3/4`
Vậy `2x^2-3x+1` đạt GTNN là `-1/8` khi `x=3/4`
`~rai~`
\(A=2x^2-3x+1\\\quad=\left(2x^2-3x+\dfrac{9}{8}\right)-\dfrac{1}{8}\\\quad=2\left(x^2-\dfrac{3}{4}+\dfrac{9}{16}\right)-\dfrac{1}{8}\\\quad=2\left(x-\dfrac{3}{4}\right)^2-\dfrac{1}{8}\\\text{Ta có:}2\left(x-\dfrac{3}{4}\right)^2\ge 0\quad\forall x\in\mathbb{R}\\\Leftrightarrow 2\left(x-\dfrac{3}{4}\right)^2-\dfrac{1}{8}\ge -\dfrac{1}{8}\quad\forall x\in\mathbb{R}\\\Leftrightarrow A\ge -\dfrac{1}{8}\quad\forall x\in\mathbb{R}.\\\text{Dấu "=" xảy ra}\Leftrightarrow \left(x-\dfrac{3}{4}\right)^2=0\Leftrightarrow x=\dfrac{3}{4}.\\\text{Vậy}\quad Min_{A}=-\dfrac{1}{8}\quad khi\quad x=\dfrac{3}{4}.\)
1939.We finally................. our teacher to go on a camping trip with us A. persuaded B. argued C. pleased D. liked 1947. He missed the lecture, so I lend him my notes ___________. A. at last B. after C. afterwards D. finally 1948. Tell me _________ what happened after Jennings hit the Minister. A. to the full B. in full C. full length D. full time 1949. Through television, __________ can see and learn about people, places, and things in faraway lands. A. TV seers B. audience C. home viewers D. TV lookers 1950. The laboratory in our school is a ____________ one. A. well-done B. well-read C. well-behaved D. well-equipped 1956. ......... Paris , London is a busy modern city. A. as B. like C. alike D. same 1957. Mrs Quyen started early ......... get to her office on time. A. in order to B. so as to C. for D. so that 1958. I‟m a bit short ........ money . can you lend me some ? A. about B. to C. for D. of 1959. If I ......... in your position , I twice before doing that. A. am / will think B. were / thought C. were / would think D. were / will think 1960. “ I wish I had seen that movie”. - “ ................. “ . A. so do I B. so had I C. but do I D. I had , too 1961. After arriving home, they usually ......... their uniforms. A. take out B. put out C. take off D. put off 1963. I wish I ...... go with you to the countryside next weekend. A. can B. could C. will be able to D. must 1965. I can‟t do that report today. I‟ve got far too much other work to________ A. catch up on B. go in for C. get away with D. cut down on 1966. While you‟re away from the office on business trips, you will be given a daily______f 25 pounds towards meals and accommodations. A. allowance B.price C. permit D. money
chỉ ra 1 hình ảnh tu từ mà em thích nhất trong 10 văn bản đã học ở lớp 6 và nêu tác dụng của hình ảnh tu từ ấy (cần gấp plss)
Thương của hai số bằng 3. Nếu tăng số bị chia 10 đơn vị và giảm số chia đi một nửa thì số thứ nhất thu được lớn hơn số thứ hai thu được là 30. Tìm hai số ban đầu
Viết cho mình chữ Phương Anh nhé,calli đó nha:333 Yc:tradi,có trang trí,tine xanh dương có đậm nhạt,vt đẹp,có tâm<3 Hóng idol:>
~Viết lại câu có nghĩa tương tự: There were several things that we had to think about before making any decision. (take) -> There were several things that we had to………….……………before making any decision. ~Tìm và sửa lỗi sai: After he had ran for half a mile,he passed the stick to the next runner.
I. Chia động từ trong ngoặc cho đúng. 1. He…………..this shirt yesterday. (buy) 2. The crowd were cheering when Nam………..the race. (win) 3. Ba is keen on………(paint). 4. Before he………………. England, he ……………English for two years. (travel- study). 5. We are happy…..good marks. (get) 6. The boys………..volleyball at this time. (play) 7. The teacher let the students…………their books when they did the test. (open) 8. They………to Lon Don since they…………married. (move-get) 9. The children………….in the river at this time last Sunday. (swim) 10. I am very tired. I……….hard all day. (work) 11. My son…………a doctor in the future. (become) 12. His father stopped……………..cigarette two years ago. (smoke) 13. Lan …………. English at the moment. (practice) 14. She …………….Ha Long Bay before. (already/ visit) 15. I ………………..fishing twice a week. (go) 16. After they……………..dinner, they……………………..TV. (have- watch) 17. Last night, I saw a thief…………the neighbor’s bike. (steal) 18. These clothes need………….(wash). They are very dirty. 19. I……….my homework while my brother and sister…………………TV (do-watch). 20. Look at them! They…………..on the trees. (climb) 21. Would you mind…………..the door? It is very hot. (open) 22. I suggest………..a shower instead of a bath to save water. (take) 23. Miss Hoa…………..a new motorcycle. (just/ buy) 24. Long……….. his girl friend a letter yesterday. (send) 25. The soccer match………….when we arrived the stadium. (already/ begin) 26. It’s no use……………that novel. It is boring. (read) 27. My father……….at this time. (sleep) 28. It is the first time I ……………… a motorcycle. (ride) 29. I…….. him yesterday. (not see) 30. She …………to Paris several times. (be) 31. We…….. a bath yet. (not take) 32. The students……………..the lessons now. (write) 33. You had better…………harder on your exam. (learn). 34. The room is very dirty. It needs…………(clean) 35. It took him an hour……………..these exercises yesterday. (do) 36. I suggest……..to school or to walk to save energy. (go) 37. I am used to …………..up early every morning. (get) GIÚP BÀI VỚI MN ƠII
Giải hộ mình nhé! 5 sao cho bạn
Chứng minh rằng: “Nếu chọn 7 số tự nhiên tùy ý thì luôn có thể chọn ra ít nhất hai số có hiệu bình phương chia hết cho 20”.
Viết 3 câu (khoảng 2-3 dòng trên vở ghi) theo kiểu đưa dẫn chứng trong đoạn văn nghị luận phục vụ cho vấn đề tình mẫu tử về nhân vật Ngô Minh Hiếu. P/s: Mọi người giúp em với ạ. Em đang cần gấp. Cảm ơn nhiều ạ.
cho khổ thơ sau : thuyền ta chầm chậm vào Ba Bể núi dựng cheo leo ,hồ im lặng lá rừng với gió ngân se sẽ họa tiếng lòng ta với tiếng chim xác định danh từ, động từ, tính từ, đại từ. -từ họa trong câu thơ cuối có nghĩa là gì
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