Вопрос школьника по предмету Математика
Из двух городов вышли одновременно навстречу друг другу два поезда и встретились через 18 часов. Найди скорость каждого поезда, если расстояние между городами 1620 км, а разность скоростей этих поездов 10 км/ч.
Ответ учителя по предмету Математика
Пусть скорость 1-го х, тогда скорость второго 10х. Так как встретились они через 18ч, а расстояние между городами 1620км, то получаем уравнение
18х+18(х+10)=1620
х+х+10=90
2х=80
х=40 км/ч — скорость первого, 50км/ч скорость второго
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ЗАРАНИЕ СПАСИБО
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а) 2/3 и 0,66
б) 5/6 + 1/4 и 1,1
в)-11 в корне и -3,4
г)3 в корне + 5 в корне и 2 в корне + 6 в корне
2.Если а>55 , b > -2 , то 4а+9b > 38