\(A=x+\dfrac{1}{x-2}\\ \Rightarrow A=x-2+\dfrac{1}{x-2}+2\)

Áp dụng BĐT Cô-si ta có:

\(A=x-2+\dfrac{1}{x-2}+2\\ \ge2\sqrt{\left(x-2\right).\dfrac{1}{x-2}}+2\\ =2\sqrt{1}+2\\ =4\)

 \(\text{Dấu "=" xảy ra}\Leftrightarrow x-2=\dfrac{1}{x-2}\\ \Leftrightarrow\left(x-2\right)^2=1\\ \Leftrightarrow\left[{}\begin{matrix}x-2=1\\x-2=-1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=3\left(tm\right)\\x=1\left(ktm\right)\end{matrix}\right.\)

Vậy \(A_{min}=4\Leftrightarrow x=3\)

\(A=x-2+\dfrac{1}{x-2}+2\ge2+2=4\)

Dấu '=' xảy ra khi x-2=1 hoặc x-2=-1

=>x=3 hoặc x=1

C₆H₁₂O₆ + 6O₂ ➝ 6CO₂ + 6H₂O

\(PTHH:C_6H_{12}O_6+6O_2\rightarrow6CO_2\uparrow+6H_2O\)

pthh

C₆H₁₂O₆ + 6O₂ \(\underrightarrow{to}\) 6CO₂\(\uparrow\) + 6H₂O

~Find mistake~

IV)

1: B=>Taken

2:C=>Be answered

3:A=>He

4:B=>Believed

5:C=>Been repaired

6:B=>had been found

7:C=>Impressed

8:A=>am helped

9:A=>weren't tell

10:B=>Repaired

V) REWRITE SENTENCE

P/s: bạn chụp làm mk nhìn đến nghẹo cổ mất,mk ghi ý chính ra,còn lại .... bạn tự biết ghi j bạn nhé .

1.Some photos are going to be taken by Lan....

2:The road isn't going to be widened.....

3:Your book needs opening/to be opened....

4:I used to be given a nice present by Tom...

5:The mixture ought to be shaked well ...

6:All the cakes ought to have been made...

7:Some new workers have to be taken on...

8:The kites have to be flown....

9:A lot of new things had to be bought..

10:He is said to be a liar.

11:The earth is believed to be rough and flat.

12:He is all known to be working for...

13:Mr.smith is thought to have just proposed...

14:He is supposed to have been running...

15:Whales are said to be hunted...