Đáp án+Giải thích các bước giải:
a, B = 8x² - 28x - 1
= 2.(4x² - 14x + $\frac{49}{4}$ ) - $\frac{51}{2}$
= 2.(2x - $\frac{7}{2}$ )² - $\frac{51}{2}$
Vì 2.(2x - $\frac{7}{2}$ )² ≥ 0 với ∀x
nên 2.(2x - $\frac{7}{2}$ )² - $\frac{51}{2}$ ≥ - $\frac{51}{2}$
Vậy min B = - $\frac{51}{2}$ khi x = $\frac{7}{4}$
b, C = (2x² + 5)²
=4x4+ 20x² + 25
Vì 4x4+ 20x² ≥ 0 với ∀x
nên 4x4+ 20x² + 25 ≥ 25
Vậy min C = 25 khi x = 0
$a)B=8x^2-28x-1$
$B=2(4x^2-14x-\dfrac{1}{2})$
$B=2(4x^2-2.2x.\dfrac{7}{2}+\dfrac{49}{4}-\dfrac{51}{2})$
$B=4(x-\dfrac{7}{2})^2-\dfrac{51}{2}\ge-\dfrac{51}{2}$
Dấu $"="$ xảy ra
`<=>`$x-\dfrac{7}{2}=0$
`<=>`$x=\dfrac{7}{2}$
Vậy $MinB=-\dfrac{51}{2}$ khi $x=\dfrac{7}{2}$
$b)C=(2x^2+5)^2\ge0$
$C=4x^4+20x^2+25\ge25$
Dấu $"="$ xảy ra `<=>`$x=0$
Vậy $MinC=25$ khi $x=0$
Giúp mik làm nhanh mấy câu này với ạ mk sắp nộp r ạ
III. Find the mistake and correct it 51. It took us quite a long time to qet here. It was a three-hours journey. 52. Although I am not interested in English but I try my best to get good marks. 53. The more I got to know Tom, the fewer I liked hịm. 54. I can’t invite you to dinner as I have my house painted at the moment. 55. The company has so little money that it can’t hardly operate anymore.
Ngày ngày mặt trời đi qua trên lăng Thấy một mặt trời trong lăng rất đỏ. "Mặt trời trong lăng" là kiểu ẩn dụ nào ?
You are going to judo class with your English friend Donna tomorrow. Write an email to Donna In your email •say where you want to meet •say what time the class starts •say what you need to take with you #camon mn trc
Giải nhanh giúp mk hứa đánh giá
Giải giúp e với Em đang cần gấp
Làm câu a,b,c nha Chi tiết rõ ràng ah 🙈
Across Down 3. sport played with a bow and arrow 1. competitive bike racing 7. long-distance race, named after a place in Greece 2. game played with hard balls and curved sticks 8. team sport where you hit a ball over a net 4. horse racing events 9. sport that involves lifting heavy objects 5. bat and ball game, played on a table (2 words) 11. a two-person game of skill, played with a foil 6. track and field sports 12. ball game played by two teams of 11 people 10. the world's biggest sporting event 15. martial art requiring strength and skill 13. played with a bat and ball on a court 16. a sport where you move through the water 14. combat sport played by people wearing gloves
Nếu đang sở sánh nhất của ttừ và trạng từ Helppppp
II. Hoàn thành câu sau với dạng đúng của 1 cụm động từ: put off look for break down get on with put on 1.They frequently have big arguments. They don't seem to .................. each other. 2.Because there was a big storm, our flight ..................... 3.Remember to .................. warm clothes. It's very cold outside. 4.I ..................... a bigger house. The current one is quite small for my family. 5.My computer.............................. , so I couldn't finish my report.
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