Question

Два автомобиля отправляются в 840 км пробег.Первый едет со скоростью на 4 км/ч больше ,чем второй ,и прибывает к финишу на 1 час раньше второго.Найти скорость первого автомобиля

Answer 1

Методом подбора получается скорость первого 60 , скорость второго 56 Проверяем 840:60 равно 14 часов, 840:56 равно 15 часов. Ответ 60 км в час двигался первый автомобиль

Answer 2

Problem Analysis

We are given two cars that are traveling a distance of 840 km. The first car is traveling at a speed that is 4 km/h faster than the second car. The first car arrives at the destination 1 hour earlier than the second car. We need to find the speed of the first car.

Solution

Let's assume the speed of the second car is x km/h. Since the first car is traveling 4 km/h faster, its speed can be represented as x + 4 km/h.

We know that the time taken by the first car to travel the distance is 1 hour less than the time taken by the second car. Let's represent the time taken by the second car as t hours. Therefore, the time taken by the first car is t - 1 hours.

We can use the formula speed = distance / time to calculate the speeds of the cars.

For the second car: x = 840 / t km/h

For the first car: x + 4 = 840 / (t - 1) km/h

To find the speed of the first car, we need to solve these two equations simultaneously.

Solving the Equations

Let's solve the equations using substitution:

From the equation for the second car, we have: x = 840 / t

Substituting this value of x into the equation for the first car, we get: 840 / t + 4 = 840 / (t - 1)

Now, we can solve this equation for t.

Calculation

Let's solve the equation to find the value of t:

**840 / t + 4 = 840 / (t -