Предмет: Математика, автор: ivansamsonov1

Два трактариста за 7дней вспахали 147га поля.Площадь поля,вспаханного первым трактаристом за 3дня,равна площади поля,вспаханным вторым трактаристом 4дня  

Сколько гектаров поля вспахал каждый тракторист за один день?

 

Ответы

Автор ответа: Mystery666
0

x=площадь поля вспаханного 1 трактаристом 

y=площадь поля вспаханного 2 трактаристом 

7*(х+у)=147

3*х=4*у

из первого уравнение подставим x во второе уравнение 

3*(21-у)=4*у

63-3*y=4*y

7*y=63

y=63/7

y=9

x=21-9

x=12

первый тракторитс вспахал 12 гектаров,а второй 9 гектаров 

Автор ответа: ρḕṱᾃᴥѠ
0

x-столько га в день делал первый, а y-второй.

3х=4y

7x+7y=147

x=12,y=9.

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Mobile Fever

Why are we so addicted to mobile phones? There are now over forty million people in Britain with mobiles and if the present trend continues, every man, woman and child in Britain will soon have one – or two, or three! They can be expensive and are possibly bad for us. You can spend a lot of money if you use your mobile a lot. According to some scientists, if we go on using mobiles, we’ll cook our brains. Some people even say that radiation from mobiles causes cancer. Teenagers are among the biggest users of mobiles, and ‘texting’ is creating a new language full of abbreviations such as ‘How RU?’ in Japan, Surveys show teenagers are reading less and mobile use is affecting the marks of secondary school learners. A big problem in Britain is crime. Last year half a million British teenagers were victims of mobile phone theft. As technology improves, mobiles can do more and more. If you have one of the new multimedia mobiles, you can log on the net, pay for things, play games, interact with TV programs and take photos to send to your friends.

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a) a little

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5. The new multimedia mobiles, you can be used for reading _______ [1]

6. Teenagers and woman are among the biggest users of mobiles _______ [1]

Total [6]


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