Question

помогите с задачей.на уроке спал не понял.автобус должен был проехать 280 км .проехал 3/8 этого расстояния автобус увеличил свою скорость на 20 км/ч найдите скорость автобуса на каждом участке движения если на весь путь было затрачено 4 часа

Answer 1

Ответ:

Пусть сначала автобус ехал со скоростью х кмч и проехал

280.2 = 40 • 3 = 120 км, затратив на этот путь

120 ч.

x

Затем он увеличил скорость на 20 км/ч, то есть, его скорость стала равной (х + 20) кмч, и оставшийся путь (280 - 120) = 160 км

он проехал за -

160 x+ 20

- ч. На весь путь автобус затратил 4 ч.

Составим уравнение: 120 160 = 4 x+ 20

120(x + 20) + 160x - 4x(x + 20) 2- 0

x(x + 20)

120x + 2400 + 160x - 4x2 - 80x - 0, x# 0; x # -20;

x(x + 20)

-4x2 + 200x + 2400 = 0 | : (-4) x2 - 50x - 600 = 0

D = 2500 + 4 • 600 = 2500 + 2400 = 4900 = v4900 = 70.

50 - 70 ＿ 20 ＿ -10 - не подходит; × =

2

2

50.4 70 ＿ 120 60 = 60 (км/ч) - скорость автобуса сначала.

22

x + 20 = 60 + 20 = 80 (км/ч) - скорость автобуса после

яS увеличения.

Ответ: 60 кмч и 80 кмч.

Объяснение:

больше не спи)))

если не трудно можно лучший ответ поставить пожалуйста)

Answer 2

Problem Analysis

To solve this problem, we need to find the speed of the bus on each segment of the journey. We are given that the bus was supposed to travel a distance of 280 km, but it only traveled 3/8 of that distance. Additionally, the bus increased its speed by 20 km/h. The total time taken for the entire journey was 4 hours.

Solution

Let's break down the problem step by step:

1. Calculate the distance traveled by the bus: Since the bus traveled 3/8 of the total distance, we can find the distance traveled by multiplying the total distance by 3/8. - Distance traveled = (3/8) * 280 km

2. Calculate the remaining distance: To find the remaining distance, subtract the distance traveled from the total distance. - Remaining distance = Total distance - Distance traveled

3. Calculate the time taken for the first segment: Since we know the distance traveled and the speed of the bus on the first segment, we can use the formula: time = distance / speed. - Time taken for the first segment = Distance traveled / Speed on the first segment

4. Calculate the time taken for the second segment: We know the remaining distance and the increased speed of the bus on the second segment. Again, we can use the formula: time = distance / speed. - Time taken for the second segment = Remaining distance / Speed on the second segment

5. Calculate the total time taken: The total time taken for the journey is given as 4 hours. We can find the time taken for the first segment and the time taken for the second segment, and then add them together to get the total time. - Total time = Time taken for the first segment + Time taken for the second segment

6. Solve the equations: We can set up two equations using the information given and solve them simultaneously to find the speeds on each segment.

Let's calculate the solution step by step.

Calculation

1. Calculate the distance traveled by the bus: - Distance traveled = (3/8) * 280 km = 105 km

2. Calculate the remaining distance: - Remaining distance = 280 km - 105 km = 175 km

3. Calculate the time taken for the first segment: - Time taken for the first segment = Distance traveled / Speed on the first segment

4. Calculate the time taken for the second segment: - Time taken for the second segment = Remaining distance / Speed on the second segment

5. Calculate the total time taken: - Total time = Time taken for the first segment + Time taken for the second segment = 4 hours

6. Set up the equations: - Equation 1: Time taken for the first segment = Distance traveled / Speed on the first segment - Equation 2: Time taken for the second segment = Remaining distance / Speed on the second segment - Equation 3: Total time = Time taken for the first segment + Time taken for the second segment

Let's solve the equations:

Equation 1: Time taken for the first segment = Distance traveled / Speed on the first segment

Equation 2: Time taken for the second segment = Remaining distance / Speed on the second segment

Equation 3: Total time = Time taken for the first segment + Time taken for the second segment

Substituting the values into the equations:

Equation 1: Time taken for the first segment = 105 km / Speed on the first segment

Equation 2: Time taken for the second segment = 175 km / Speed on the second segment

Equation 3: 4 hours = (105 km / Speed on the first segment) + (175 km / Speed on the second segment)

Now we have a system of equations that we can solve to find the speeds on each segment.

Unfortunately, the specific values for the speeds on each segment are not provided in the given information. Therefore, we cannot provide a specific answer to this problem without additional information.

Please provide the specific values for the speeds on each segment, and we will be able to calculate the solution for you.