Пошаговое объяснение:
There is bath in the bathroom
There is mirror in the bathroom
There is armchair in the hall
There is carpet in the hall
There is sofa in the hall
There are curtains in the hall
There are cushions in the hall
There is painting in the hall
There is cooker in the kitchen
There is chair in the kitchen
There is table in the kitchen
There is sink in the kitchen
There is fridge in the kitchen
There are pillows in the bedroom
There is desk in the bedroom
There is poster in the bedroom
There is wardrobe in the bedroom
There is bookcase in the bedroom
There are stairs leading from the first to the second floor
9 ч 24 мин = 9 ч + (24 : 60) ч = 9 ч + 0,4 ч = 9,4 ч
Пусть х км/ч - собственная скорость катера, тогда (х + 6) км/ч - скорость катера по течению реки, (х - 6) км/ч - скорость катера против течения реки. Уравнение:
72/(х+6) + 72/(х-6) = 9,4 - 3
72 · (х - 6) + 72 · (х + 6) = 6,4 · (х - 6) · (х + 6)
72х - 432 + 72х + 432 = 6,4 · (х² - 6²)
144х = 6,4х² - 230,4
6,4х² - 144х - 230,4 = 0
D = b² - 4ac = (-144)² - 4 · 6,4 · (-230,4) = 20736 + 5898,24 = 26634,24
√D = √26634,24 = 163,2
х₁ = (144-163,2)/(2·6,4) = (-19,2)/(12,8) = - 1,5
х₂ = (144+163,2)/(2·6,4) = (307,2)/(12,8) = 24
ответ: 24 км/ч - собственная скорость катера.
Пошаговое объяснение:
