Question

Помогите пожалуйстачерез 2 часа после выхода со станции А тепловоз увеличил скорость на 12 км/ч и через 5 часов после начала движения прибыл в пункт В. каково была скорость тепловоза в начале пути, если расстояние от А до В равно 261 км?

Answer 1

Начальная скорость V = х , Время пути t = 2 ч, Расстояние S =  2 * х
Скорость увеличена V = х + 12 , Время пути t = 5 - 2 = 3 часа
Расстояние общее  S = 261 км

2х + 3 * ( х + 12 ) = 261
2х + 3х + 36 = 261
5х = 261 - 36
5х = 225
х = 225 : 5
х = 45 км/ч начальна скорость
Значит изначально он проехал S = 2 * 45 = 90 км
После увеличил скорость и проехал S = (45 + 12) * (5 - 2) = 57 * 3 = 171 км
S = 171 + 90 = 261 км

Answer 2

Предположим, скорость тепловоза сначала была равна Х км/ч, после того, как он увеличил скорость, она стала равна Х+12 км/ч. Составляем уравнение
2*Х+(5-2)*(Х+12)=261
2Х+3Х+36=261
5Х=225
Х=45 км/ч - вот такой была скорость в начала движения

Answer 3

Problem Analysis

We are given that a locomotive (referred to as "тепловоз" in Russian) departs from station A and increases its speed by 12 km/h after 2 hours. After 5 hours of travel, it arrives at station B, which is 261 km away from station A. We need to determine the locomotive's initial speed.

Solution

Let's denote the initial speed of the locomotive as x km/h. We can use the formula distance = speed × time to solve this problem.

The locomotive traveled for 2 hours at the initial speed x km/h, so the distance covered during this time is 2x km.

After 2 hours, the locomotive increased its speed by 12 km/h. Therefore, for the remaining 5 hours of travel, the locomotive's speed was (x + 12) km/h. The distance covered during this time is 5(x + 12) km.

The total distance traveled from station A to station B is 261 km. Therefore, we can write the equation:

2x + 5(x + 12) = 261

Now, let's solve this equation to find the value of x.

2x + 5x + 60 = 261

7x + 60 = 261

7x = 201

x = 201 / 7

x ≈ 28.71

Therefore, the locomotive's initial speed was approximately 28.71 km/h.

Answer

The locomotive's initial speed was approximately 28.71 km/h.