Minh tinh dc la 6130 kg.day la ket qua chinh xac

Ta can quy dong nhu sau

2/5=2/5.7=14/35

3/7=3/7.5=15/35 con phan so 9/35 da cung mau voi 2 phan so da quy dong nenkhong ca 

Zay do 

\(\frac{x}{y}=\frac{7}{-9}=>x=\frac{-7}{9}.y\)

Ta có: \(x+y=18\)

\(=>\frac{-7}{9}.y+y=18\)

\(=>\frac{2}{9}.y=18\)

\(=>y=18:\frac{2}{9}=18.\frac{9}{2}=81\)

\(=>x=\frac{-7}{9}.81=-63\)

vậy x = -63, y = 81

Ủng hộ mk nha ^_-

$A=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2005}-\frac{1}{2006}=(1+\frac{1}{2}+...+\frac{1}{2006})-(1+\frac{1}{2}+..+\frac{1}{1003})=\frac{1}{1004}+\frac{1}{1005}+...+\frac{1}{2006}$

Lại có  $\frac{1}{3010}.B=\frac{1}{1004}+\frac{1}{2006}+\frac{1}{1005}+\frac{1}{2005}+...+\frac{1}{1004}=\frac{1}{1505}(\frac{1}{1004}+\frac{1}{1005}+...+\frac{1}{2006})$

Suy ra A/B = 1505

Tham khảo nha 

Rock and Roll is more exciting than classicad music ( not as ... as )

⇒ Rock and Roll is not as boring as classical music

This movie is more interesting than the one we saw yesterday.

⇒ The movie we saw yesterday is not as intesting as this movie

Chia V

1. Her uncle (be) was on his farm 3 weeks ago.

2. Where you (go) go this morning? - I (visit) visited my grandparents in the countryside.

3. We (play) will play football if the weather (be) is fine tomorrow.

4. How long you (live) lived here? - For 10 years

5. These (be) was an international foodball match on TV last night but I (cannot) (see) couldn't see it because I (have) (do) has to dolots of homework