Ответ учителя по предмету Математика
Напишем условия, которые нам даны:
Vпо теч. = 8км/ч
Vпротив теч. = 6км/ч
Sпо теч. = Sпротив теч.
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Пусть, Sпо теч. = Sпротив теч. = S
Тогда, S/8 + S/6 <= 3
Приведём к общему знаменателю:
2S/16 + 3S/16 <= 3
5S/16 <= 3
5S <= 48
S <= 9,6 км
tпо теч. = S/8
S = 8*tпо теч.
8*tпо теч.<= 9,6 км
tпо теч. <=1,2 ч
tпротив теч. = S/6
S = 6*tпротив теч.
6*tпротив теч.<= 9,6 км
tпротив теч. <=1,6 ч
Ответ: tпротив теч. <=1,6 ч, tпо теч. <=1,2 ч
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