\(P=\sqrt{x^2+\frac{1}{x^2}}+\sqrt{y^2+\frac{1}{y^2}}\)

\(\ge\sqrt{\left(x+y\right)^2+\left(\frac{1}{x}+\frac{1}{y}\right)^2}\) ( min cốp sờ ki )

\(\ge\sqrt{\left(x+y\right)^2+\frac{16}{\left(x+y\right)^2}}\) ( cau chy sờ goát )

\(=\sqrt{4^2+\frac{16}{4^2}}=\sqrt{17}\)

Dấu "=" xảy ra tại \(x=y=2\)

Is that true.Xem ra cách t đỡ sốc hơn cách m nếu đúng:v

what is your name?

How old are you?

 Who always drives his customers away?

 What is the longest word in the English language?

NHỚ GIẢI THÍCH=ANH +VIỆT

ĐÚNG TUI TICK CHOA

Look and say. (6 points)

1. Hello, ________.

2. I have a ________.

3. This is ________. 

4. There's ________. 

5. Touch ________. 

Để \(\frac{\sqrt{x+1}}{\sqrt{x-2}}=\sqrt{\frac{x+1}{x-2}}\) là số nguyên thì \(\frac{x+1}{x-2}\) là số chính phương

Khi đó \(x+1⋮x-2\)

\(\Leftrightarrow x-2+3⋮x-2\)

\(\Leftrightarrow3⋮x-2\)

\(\Leftrightarrow x-2\in\left\{1;3;-1;-3\right\}\)

\(\Leftrightarrow x\in\left\{4;5;1;-1\right\}\)

Thay vào thử nha !

II/ Choose the best answer.

1.     Mai hates eating fast food because it’s not good ……her health.

a.      on           b. for           c. at             d. in

2.     If you want to live long, you …… eat  much red meat.

a.      should              b. needn’t    c. have to    d. shouldn’t

3.      Don’t read in bed, ................ you’ll harm your eyes.

a.      or            b. and                   c. but           d. so