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Вычислить значение выражения 5x^2+(2xy+4x^2)−(6xy+9x^2) при x=1, y=2
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Предмет:
Алгебра -
Автор:
bradleycarroll - 6 лет назад
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Ответы 4
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Там 9x^2 сокращается
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Автор:
eaglegk9n - 6 лет назад
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0
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спс
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Автор:
troyg747 - 6 лет назад
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0
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Незачто
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Автор:
encarnaciónmgst - 6 лет назад
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0
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Решение: 5x^2+2xy+4x^2-6xy-9x^2=-4xy=-4*1*2=-8
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Автор:
ignacioked1 - 6 лет назад
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0
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срочно!!нужна помощь!!!
1)перевод текста
2)ответы на вопросы
Many animals can swim without being taught how. People are not so fortunate. They have to learn to swim. But it is very much worthwhile to learn to swim for three reasons: swimming is fun. It is good exercise for building strong bodies. And being able to swim takes away most of the danger from boating, water skiing, and other water sports. There are four styles of sports swimming: freestyle (crawl), backstroke, breaststroke and butterfly.
Swimming is so popular that many public swimming pools have been built. Many public beaches have been set up.
Swimming is one of the sports that make up the Olympic Games. Swimmers from all over the world compete in these games.
It may seem strange that swimming was not included in ancient Olympic Games, though people had known it long ago. Both in ancient Greece and Rome swimming was as important as reading. Soldiers often sailed to other lands and fought on seas too. They wore (.might swimming for life-saving.
As a sport swimming was practiced in Japan. There swimming contests were held before the new era. Since the 17th century it has been taught in schools. But the Japanese did not lei, foreigners into their country. That is why it were Europeans who developed swimming and made it a sport.
One of the earliest swimming competitions in Europe was held in 1515 in Venice. In 1538, the first swimming handbook was published. First swimming schools began to appear in the end of the 18th century. Swimmers trained and contested mostly in rivers, ponds and lakes, which was only possible in summer. In the 19th century covered pools appeared and swimming became very popular.
Many countries organized national swimming championships, and the first European championship was held in 1890. Six years later, swimming became the Olympic sport and in 1908 the International Swimming Federation was formed. Oddly enough, the first world championship was only held in 1973, or 65 years later!
Swimming as a sport was not popular in Russia. Training and competitions were only possible in summer and sportsmen could not achieve good results. The first swimming competitions in Russia were held in 1913 in Kiev.
Things changed after the Revolution. Swimming schools opened in Moscow in the 20s. And in the 30s first covered pools were built. Soviet swimmers could train all the year round and they did well.
Regular swimming championships of the Soviet Union have been
held since 1928. And since 1947 our swimmers have been taking part
in international competitions. Many of them have achieved good results
and set new records. Among them are G. Prozumenshchikova (Stepanova),
S. Babanina, V. Salnikov and others.
Questions
1. Why is it worthwhile to learn to swim?
2. How many styles are there in swimming?
3. Where was swimming practiced as a sport?
4. When did swimming become very popular?
5. Was swimming as a sport popular in Russia?
6. What famous Soviet swimmers do you know?-
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Автор:
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Ответов:
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Треугольник ABCD вписан в окружность с центром в точке O. Точки O и C лежат в одной плоскости относительно прямой AB. Найдите угол ACB, если угол AOB равен 59°. Ответ дайте в градусах.
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