Question

катер прошёл 60 км по течению реки 20 км против течения реки за 5 часов скорость течения реки напротив пути составляет 3 км ч Найдите собственную скорость катера​

Answer 1

Ответ:

15 км/ч

Пошаговое объяснение:

Пусть собственная скорость лодких км/ ч, тогда её скорость по течению ҳ+3 км/ ч, против течения Х-3 км/ч. Составим уравнение:

20/(x-3) + 60/(х+3) = 5

20ҳ+60+60x-180-5х2+45=0

х2-16х+15=0

По теореме Виета x=-1 (не подходит) х=15

Answer 2

Calculating the Boat's Speed

To find the boat's speed, we can use the formula: boat's speed = (boat's speed in still water + current speed) - (boat's speed against the current)

Given: - Distance traveled with the current = 60 km - Distance traveled against the current = 20 km - Time taken = 5 hours - Current speed = 3 km/h

Using the formula, we can calculate the boat's speed.

Calculating Boat's Speed in Still Water

Let's denote the boat's speed in still water as b.

The boat's speed with the current can be calculated using the formula: 60 = (b + 3) * 5 This is derived from the fact that the boat's speed with the current is the sum of the boat's speed in still water and the current speed, multiplied by the time taken.

Solving for b: 60 = 5b + 15 5b = 60 - 15 5b = 45 b = 9

So, the boat's speed in still water is 9 km/h.

Conclusion

Therefore, the boat's speed in still water is 9 km/h.