Số người ghét: 50

Số người yêu: 30

Suy luận logic là ra.

Bài này Tiểu Học đâu ra lớp 8.

bạn giải theo phương trình sẽ là lớp 8, hãy suy nghĩ tinh tế lên một chút

1.will phone

2.will sit 

3.will watch

4.will work

5.will you do...

6.will wait

7.will Tom meet

8.will get

9.will study

10.will use

1. Mai....are going to phone..........(phone) her grandparents at seven o'clock tomorrrow

2. This time next week,I (sit)......will sit.....on the beach in Nha Trang

3. At 7 o'clock tonight,I ( watch) ......am going to watch .......... the news

4. At 3 o'clock tomorrow, I (work)......am going to work ........in my office

5. What ( you/do).........are you going to do..........this time tomorrow ?

6. At 5o'cloock tomorrow afternoon, he ( wait) .......is going to wait ............for his train

7. ( Tom/meet)..........Will Tom meet........... me when I arrive at the airport?

8. This time tomorrow , we ( get)..............are going to get............ready to go out

9. At 9 o'clock tomorrow morning,she ( study) ......is going to study......... in the library

10. We.....will use ....... a universal translator to deal with any foreign language ( use )

\(\frac{a-b}{b+c}+\frac{b-c}{c+d}+\frac{c-d}{a+d}\ge\frac{a-d}{a+b}\)

\(\Leftrightarrow\frac{a-b}{b+c}+\frac{b-c}{c+d}+\frac{c-d}{a+d}-\frac{a-d}{a+b}\ge0\)

\(\Leftrightarrow\frac{a-b}{b+c}+\frac{b-c}{c+d}+\frac{c-d}{a+d}+\frac{d-a}{a+b}\ge0\)

\(\Leftrightarrow\left(\frac{a-b}{b+c}+1\right)+\left(\frac{b-c}{c+d}+1\right)+\left(\frac{c-d}{a+d}+1\right)+\left(\frac{d-a}{a+b}+1\right)\ge4\)

\(\Leftrightarrow\frac{a+c}{b+c}+\frac{b+d}{c+d}+\frac{c+a}{a+d}+\frac{d+b}{a+b}\ge4\)

\(\Leftrightarrow\left(a+c\right)\left(\frac{1}{b+c}+\frac{1}{a+d}\right)+\left(b+d\right)\left(\frac{1}{c+d}+\frac{1}{a+b}\right)\ge4\)(1)

Áp dụng BĐT AM-GM ta có:

\(\frac{a+c}{b+c}+\frac{b+d}{c+d}+\frac{c+a}{a+d}+\frac{d+b}{a+b}\ge\)\(\left(a+c\right)\frac{2}{\sqrt{\left(b+c\right)\left(a+d\right)}}+\left(b+d\right)\frac{2}{\sqrt{\left(c+d\right)\left(a+b\right)}}\ge\frac{4\left(a+c\right)}{a+b+c+d}+\frac{4\left(b+d\right)}{a+b+c+d}=\frac{4\left(a+b+c+d\right)}{a+b+c+d}=4 \left(2\right)\)Từ (1) và (2) \(\Rightarrow\frac{a-b}{b+c}+\frac{b-c}{c+d}+\frac{c-d}{a+d}\ge\frac{a-d}{a+b}\)

Dấu " = " xảy ra \(\Leftrightarrow\hept{\begin{cases}\frac{1}{b+c}=\frac{1}{a+d}\\\frac{1}{c+d}=\frac{1}{a+b}\end{cases}}\Leftrightarrow\hept{\begin{cases}b+c=a+d\\c+d=a+b\end{cases}}\Leftrightarrow a=b=c=d\)

vì sao                                          

 (a+c)(2/căn bậc 2 của(b+c)(a+d))+(b+d)(2/căn bậc 2 của (c+d)(a+b))
>=(4(a+c)/a+b+c+d) +4(b+d)/a+b+c+d

(căn bậc 2 máy mink ko viết đc)

Ta có: \(\frac{x^2}{y^2}+\frac{y^2}{x^2}\ge\frac{x}{y}+\frac{y}{x}\)

\(\Leftrightarrow\frac{x^4+y^4}{x^2y^2}\ge\frac{x^2+y^2}{xy}\Leftrightarrow\frac{x^4+y^4}{x^2y^2}\ge\frac{x^3y+xy^3}{x^2y^2}\)

\(\Leftrightarrow x^4+y^4\ge x^3y+xy^3\Leftrightarrow x^4+y^4-x^3y-xy^3\ge0\)

\(\Leftrightarrow x^3\left(x-y\right)-y^3\left(x-y\right)\ge0\Leftrightarrow\left(x-y\right)^2\left(x^2+xy+y^2\right)\ge0\)(đúng)

Các phép biến đổi là tương đương suy ra đpcm
Dấu "=" xảy ra khi x=y

cám ơn bạn nha

tonardo

aid

noise

put out

evacuate

part2

1.to ; 2.at; 3.have; 4.and; 5.from

Part 1:, Use the words from the box to complete the sentences : put out, tonardo, evacuate, noise pollution, aid

1. ........Tornadoes...... is a violent storm with very strong winds which move in a circle 
2. The rescue workers set up a camp to provide.........Hurricanes .for the flood victims
3. .....Earthquakes.......... occurs because there are too many loud sounds in the environment 
4. Rescue workers are still trying to..........Floods and Tsunami.....the forest fire

5,The police had to...house fire......the village to public shelter before the volcano started to erupt

Part 2: complete the email. Write ONE word for each space  

Hi Marie,

Can you help me? I want(1).....to.........make a birthday card for my grandma. I know you're very good(2)........at........art, so (3)......has...........you got any ideas? Grandma loves animals. She has three cats, two dogs(4).........and.........two horses. Do you think I should paint one(5)........of.........her animals for the cards?

ta co ph trinh

45x=60(x-50)

x=200 km

cho mk cai h nha

còn cách nào khác không bạn