Question

Помогите пожалуйста, очень прошу Две бригады рабочих должны проложить по 720 м кабеля. Первая прокладывала каждый час на 2 м больше второй и закончила работу на 18 часов раньше нее. Сколько метров кабеля прокладывала каждый час каждая бригада?

Answer 1

$\frac{720}{x} - \frac{720}{x+2} =18 720(x+2)-720x=18x(x+2) 720x+1440-720x=18x^{2} +36x 18x^{2}+36x-1440=0 x^{2}+2x-80=0 x_{1} + x_{2} =-10 x_{1} * x_{2} =8 720/8=90 720/(8+2)=72$

Answer 2

Problem Analysis

We have two teams of workers who are laying cables. The first team lays 2 meters more cable per hour than the second team. The first team finished their work 18 hours earlier than the second team. We need to determine how many meters of cable each team laid per hour.

Solution

Let's assume that the second team laid x meters of cable per hour. Since the first team laid 2 meters more per hour, they laid (x + 2) meters of cable per hour.

We know that the first team finished their work 18 hours earlier than the second team. Let's assume that the first team worked for t hours. Therefore, the second team worked for (t + 18) hours.

To find the total length of cable laid by each team, we can multiply the number of hours worked by the number of meters laid per hour.

For the first team: Total length of cable laid by the first team = (x + 2) * t

For the second team: Total length of cable laid by the second team = x * (t + 18)

Since both teams are laying the same length of cable (720 meters), we can set up the following equation:

(x + 2) * t = x * (t + 18) = 720

Now, let's solve this equation to find the values of x and t.

Calculation

(x + 2) * t = x * (t + 18) = 720

Expanding the equation: xt + 2t = xt + 18x

Simplifying the equation: 2t = 18x

Dividing both sides by 2: t = 9x

Substituting the value of t in terms of x into the equation: 9x = 18x

Subtracting 9x from both sides: 0 = 9x

Dividing both sides by 9: x = 0

Since x = 0, it means that the second team did not lay any cable per hour. This implies that the first team laid all the cable.

Therefore, the first team laid 720 meters of cable per hour.

Answer

The first team laid 720 meters of cable per hour, while the second team did not lay any cable per hour.