Предмет: Алгебра, автор: rjktcybrjdfkbpf

Лодка проплыла 18 км. по течению реки и 6 км. против течения, затратив на весь путь 4ч. Чему равна собственная скорость лодки, если скорость течения равна
3 км. в час!

Ответы

Автор ответа: ahta

х км/ч собственная скорость лодки, (х+3) км/ч - скорость по течению, 18/(х+3) ч - время затраченное по течению. (х-3) км/ч - скорость против течения. 6/(х-3) ч - время затраченное против течения. 18/(х+3) +6/(х-3) =4 , 18(х-3)+6(х+3)=4(х-3)(х+3), 18х-54+6х+18=4х²-36, 4х²-24х=0, 4х(х-6)=0, х1=0, х2=6
6 км/ч - собственная скорость лодки

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