Question

Теплохід за 2 год пройшов 30 км по озеру і 12 км за течією річки.Знайти швидкість теплохода під час руху по озеру, якщо швидкість течії річки дорівнює 4км/год. ЗАДАЧА НА СКЛАДАННЯ СИСТЕМИ!!!​

Answer 1

Ответ:

Составим уравнение

теплоход по озеру двигался за время 30/V, по реке - 12/(V+4) и всего было потрачено 2 часа

\frac{30}{v} + \frac{12}{v+4} =2

30*(v+4)+12v=2(v*(v+4))

30v+120+12v=2v^2+8v

2v^2-34v-120=0

v^2-17v-60=0

v1=20

v2=-3

поскольку скорость не может быть отрицательной

V=20 км/час

Объяснение:

Answer 2

To find the speed of the boat during its movement on the lake, we can set up a system of equations based on the given information.

Let's assume the speed of the boat in still water is x km/h.

Speed on the lake:

When the boat is moving on the lake, there is no current affecting its speed. Therefore, the speed of the boat on the lake is equal to its speed in still water, which is x km/h.

Speed against the river current:

When the boat is moving against the current of the river, the effective speed of the boat is reduced by the speed of the current. In this case, the speed of the current is given as 4 km/h. Therefore, the effective speed of the boat against the current is (x - 4) km/h.

Distance traveled on the lake:

The boat traveled a distance of 30 km on the lake in 2 hours. We can use the formula distance = speed × time to set up an equation: 30 = x × 2.

Distance traveled against the river current:

The boat traveled a distance of 12 km against the river current. We can again use the formula distance = speed × time to set up another equation: 12 = (x - 4) × 2.

Now, we have a system of two equations: 1. 30 = 2x 2. 12 = 2(x - 4)

We can solve this system of equations to find the value of x, which represents the speed of the boat in still water.

Solving equation 1 for x: 30 = 2x Dividing both sides by 2: 15 = x

Substituting the value of x into equation 2: 12 = 2(x - 4) 12 = 2(15 - 4) 12 = 2(11) 12 = 22

The equation 12 = 22 is not true, which means there is no solution for this system of equations. It seems there might be an error in the given information or the problem statement.

Please double-check the values and conditions provided in the problem.