-
Вопрос по другим предметам:
Из точки А в точку Б расстояние 50км!одновременно выехали вел и мот.известно что за час мотоцикл проезжает на 30км больше-
Автор:
coal
-
-
Допустим, что скорость велосипедиста равна х км/ч, тогда скорость мотоциклиста равна х + 30 км/ч.
С такой скоростью велосипедист проедет 50 км за 50/х часов, а мотоциклист тоже расстояние проедет за 50/(х + 30) часов.
По условию задачи, велосипедист приехал на 3/2 часа позже, значит мы можем составить следующее уравнение:
50/х - 3/2 = 50/(х + 30),
(100 - 3 * х)/2 * х = 50/(х + 30),
100 * х + 3000 - 3 х² - 90 * х = 100 * х,
-3 * х² - 90 * х + 3000 = 0.
Найдём дискриминант данного уравнения:
(-90)² - 4 * (-3) * 3000 = 44100.
Так как х может быть только положительным числом, то уравнение имеет единственное решение:
х = (90 - 210)/-6 = 20.
Ответ: 20 км/ч.
-
Вопрос по другим предметам:
периметр осевого сечения цилиндра 6см, при каком радиусе основания цилиндра его объема будет наибольшим?-
Ответов: 1
-
3 года назад
-
-
Вопрос по другим предметам:
Найдите сумму 75 первых членов последовательности, общий член который определяется формулой: an=3n-19. Доказать, что-
Ответов: 1
-
3 года назад
-
-
Вопрос по английскому языку:
Помогите с пересказом текста.
It was Friday evening and shopkeepers in Grimsby came to the Midland Bank to put their money into the night safe . But later that evening the night safe disappeared and with it $ 4,000 . Every Friday evening the shopkeepers put the money they take during the week into the night safe . They don't want leave it in their shops , but the bank closes early . The night safe is outside on the wall and the money they put into it goes into the bank . But on this Friday evening the people who came along the street with their bags full of money dropped them not into a night safe , but into a box that belonged to Mr. Mi chael Bell . Mr. Bell , who makes radios and televisions , had the idea when he saw two men outside the bank one evening . When he came home from work , the two men , who were apparently shopkeepers , were putting some money into the night safe . He made the box at home and painted it . When it was ready , he took it to the bank and hung it on the wall next to the night safe . On the front of the night safe he painted the words : " Please use the new night safe . This one is out of order . " Then he went round the corner and waited for the shopkeepers to arrive . He listened while they dropped their bags money into the box . When it was full , he quickly took it down and went hom with $ 4,000 . Mr. Bell is very clever and his idea was good , but not perfec Now he has time to think of other ideas . He's in prison for stealing .
-
Ответов: 1
-
3 года назад
-
-
Вопрос по английскому языку:
Помогите с пересказом текста.
It was Friday evening and shopkeepers in Grimsby came to the Midland Bank to put their money into the night safe . But later that evening the night safe disappeared and with it $ 4,000 . Every Friday evening the shopkeepers put the money they take during the week into the night safe . They don't want leave it in their shops , but the bank closes early . The night safe is outside on the wall and the money they put into it goes into the bank . But on this Friday evening the people who came along the street with their bags full of money dropped them not into a night safe , but into a box that belonged to Mr. Mi chael Bell . Mr. Bell , who makes radios and televisions , had the idea when he saw two men outside the bank one evening . When he came home from work , the two men , who were apparently shopkeepers , were putting some money into the night safe . He made the box at home and painted it . When it was ready , he took it to the bank and hung it on the wall next to the night safe . On the front of the night safe he painted the words : " Please use the new night safe . This one is out of order . " Then he went round the corner and waited for the shopkeepers to arrive . He listened while they dropped their bags money into the box . When it was full , he quickly took it down and went hom with $ 4,000 . Mr. Bell is very clever and his idea was good , but not perfec Now he has time to think of other ideas . He's in prison for stealing .
-
Ответов: 1
-
3 года назад
-