\(P=3\left(\frac{1}{a^2+b^2}+\frac{1}{2ab}\right)+\frac{1}{2ab}\ge\frac{3.4}{a^2+b^2+2ab}+\frac{2}{\left(a+b\right)^2}=\frac{14}{\left(a+b\right)^2}=14\)

Dấu "=" xảy ra khi \(a=b=\frac{1}{2}\)

( 1 + 3 + 5 + 7 + ... + 2003 + 2005 ) x ( 1212 x 27 - 2727 x 12 )

= ( 1 + 3 + 5 + 7 + ... + 2003 + 2005 ) x ( 32724 -32724 )

= ( 1 + 3 + 5 + 7 + ... + 2003 + 2005 ) x 0

= 0

vu cao minh sai roi

de keu la tinh nhanh ma

Thì thế gọi là tính nhanh còn gì

vào youtube bạn ơi

Nửa chu vi hình chữ nhật là:

340 : 2 = 170 m

Chiều dài hình chữ nhật là:

(170 + 50) : 2 = 110 m

Chiều rộng hình chữ nhật là:

170 - 110 = 60 m

Diện tích hình chữ nhật là:

110 x 60 : 2 = 3300 m²

Đáp số : 3300 m²

Mình nhầm,xin lỗi bạn

Chiều daì là chieu rộng mình nhầm 

Chiều dài là:60+50=110(m)

DT là:110x60x110=6600(m)

Đáp số:6600m

1, Ba is a good badminton player .

\(\rightarrow\) He plays badminton well .

2, Lan is a slow runner .

\(\rightarrow\) She runs slowly .

3, Mrs.Thanh is a quick swimmer .

\(\rightarrow\) He swims quickly .

4, Mrs.Vui is a safe cyclist .

\(\rightarrow\) She cycles safely .

5, Lan's father is a careful driver .

\(\rightarrow\) He drives carefully .

6, My mother is a good cook .

\(\rightarrow\) She cooks well .

7, My sister is a beautiful dancer .

\(\rightarrow\) She dances beautifully .

8, Nam and Ba are skillful soccer player .

\(\rightarrow\) They play soccer skillfully .

9, Mr.Tuan and Mr.Nam are careless driver .

\(\rightarrow\) They drives careless .

10, We should finish our homework first .

\(\rightarrow\) We must finish our homework first .

11, Lan must tidy the house everyday .

\(\rightarrow\) Lan has to tidy the house everyday .

12, Ba ought to cook lunch for his mother .

\(\rightarrow\) Ba has to cook lunch for his mother .

1. Ba is a good badminton player

= Ba plays badminton well.( ko có goodly nha )

5. Lan's father is a careful taxi driver

= He drives taxi carefuly

6. My mother is a good cook

= She cooks well.

7. My sister is a beautiful dancer.

= She dances beautifully

8. Nam and Ba are skillful soccer players

= They are play soccer skillfully

9. Mr. Tuan and Mr. Nam are careless driver.

= They drive car carlessly

10. We should finish our homework first.

= We must finish our homework first.

11. Lan must tidy the house everyday

= Lan has to tidy the house everyday.

12. She ought to cook lunch for his mother

= Ba has to cook lunch for his mother

Mk k chắc đúng đâu,kém phần này lắm.

5.He drives taxi is carefully .

6.She cooks is good.

7.She dance is beautifully.

8.They play soccer are skillfully.

9.They drive are carelessly.

10.We must finish our homework.

11.Lan has to tidy the house everyday.

12.Ba has to cook lunch for his mother.

Có linh cạm sai nhiều lắm.

a, \(A=\left(\frac{a\sqrt{a}-1}{a-\sqrt{a}}-\frac{a\sqrt{a}+1}{a+\sqrt{a}}\right):\frac{a+2}{a-2}\) \(\left(a>0;a\ne2\right)\)

\(=\left[\frac{\left(\sqrt{a}-1\right)\left(a+\sqrt{a}+1\right)}{\sqrt{a}\left(\sqrt{a}-1\right)}-\frac{\left(\sqrt{a}+1\right)\left(a-\sqrt{a}+1\right)}{\sqrt{a}\left(\sqrt{a}+1\right)}\right]:\frac{a+2}{a-2}\)

\(=\frac{a+\sqrt{a}+1-a+\sqrt{a}-1}{\sqrt{a}}.\frac{a-2}{a+2}\)

\(=\frac{2\sqrt{a}}{\sqrt{a}}.\frac{a-2}{a+2}\)

\(=\frac{2\left(a-2\right)}{a+2}\)

b, Để: \(A=1\Leftrightarrow\frac{2\left(a-2\right)}{a+2}=1\)

\(\Rightarrow\frac{2a-4-a-2}{a+2}=0\)

\(\Rightarrow\frac{a-6}{a+2}=0\)

\(\Rightarrow a-6=0\)

\(\Rightarrow a=6\left(tm\right)\)

Vậy...........................