Предмет: Математика, автор: annad080107

Два автомобиля выехали одновременно из городов А и В навстречу друг другу Через 2 ч. они встретились и, не останавливаясь, продолжили движение. Первый автомобиль прибыл в А на 3 чраньше, чем второй в город В. Найдите скорость второго автомобиля (км/ч), если расстояние между городами составляет 294 км.​


Simba2017: класс какой
annad080107: 8 класс
Simba2017: пусть х скорость первого, у-скороть второго
Simba2017: тогда x+y=294/2
Simba2017: это уравнение понятно?
annad080107: да
Simba2017: и второе 294/x+3=294/y
Simba2017: система 2 уравнений

Ответы

Автор ответа: meewpus
1

Скорость первого ---х км/ч

Скорость второго ----у км/ч

Их скорость сближения (суммарная скорость) x+y = 352 /4 = 88 км/ч

Время первого, затраченное на весь путь -----352 / х часов

Время второго, затраченное на весь путь ---352/y = 352/( 88-x) км/ч

Разница во времени ---1ч 28 мин или 1 7/15 часа или 22/15 часа

Уравнение:

352/ (88 -х) - 352/х =22/15

Решаешь это квадратное уравнение (сама) и получаешь х = 48 км/ч

Второй корень отрицательный, он не нужен

Итак, скорость первого ---48 км/ч

Скорость второго -------88-48 = 40 км/ч

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