Question

Срочно дана дрбь, числитель которой на 5 меньше знаменателя, если увеличить числитель данной дроьи на 2 , а знаменатель втрое то получится 4/21 найди исходную дробь ещё одна задача из двух городов расстояние между которыми составляет 425 км, навстречу друг другу выехали два автомобиля. скорость первого на 10 км ч меньше второго. проехав 200 км первый автомобиль встретился со вторым найди скорость второго автомобиля​

Answer 1

Ответ:

2/7

скорость была 90 км/ч

Объяснение:

1)в первом просто 4÷2=2 21÷3=7

2)

200/(v-10)=225/v

200v=225v-2250

2250=25v

v=90

Answer 2

Problem 1: Finding the Original Fraction

To find the original fraction, let's assign variables to the numerator and denominator of the fraction. Let's call the numerator "x" and the denominator "y".

According to the problem, the numerator of the given fraction is 5 less than the denominator. So we can write the equation:

x = y - 5

If we increase the numerator by 2 and the denominator by 3, we get the fraction 4/21. We can write another equation based on this information:

(x + 2) / (y + 3) = 4/21

Now we have a system of two equations with two variables. We can solve this system to find the values of x and y.

Let's solve the system of equations:

Equation 1: x = y - 5 Equation 2: (x + 2) / (y + 3) = 4/21

To solve Equation 1, we can substitute the value of x from Equation 1 into Equation 2:

(y - 5 + 2) / (y + 3) = 4/21

Simplifying the equation:

(y - 3) / (y + 3) = 4/21

Cross-multiplying:

21(y - 3) = 4(y + 3)

Expanding:

21y - 63 = 4y + 12

Bringing like terms together:

21y - 4y = 12 + 63

Simplifying:

17y = 75

Dividing both sides by 17:

y = 75 / 17

Simplifying the fraction:

y ≈ 4.41

Now, substitute the value of y back into Equation 1 to find x:

x = 4.41 - 5

x ≈ -0.59

Therefore, the original fraction is approximately -0.59/4.41.

Problem 2: Finding the Speed of the Second Car

In this problem, two cars start from different cities and meet each other after traveling a certain distance. The speed of the first car is 10 km/h less than the speed of the second car. We need to find the speed of the second car.

Let's assign variables to the speeds of the first and second cars. Let's call the speed of the first car "v1" and the speed of the second car "v2".

According to the problem, the speed of the first car is 10 km/h less than the speed of the second car. So we can write the equation:

v1 = v2 - 10

After traveling 200 km, the first car meets the second car. We can use the formula:

Distance = Speed × Time

To find the time taken by the first car to travel 200 km, we divide the distance by the speed:

Time = Distance / Speed

For the first car:

t1 = 200 / v1

For the second car:

t2 = 200 / v2

Since both cars started at the same time and met each other, their travel times are equal:

t1 = t2

Substituting the values of t1 and t2:

200 / v1 = 200 / v2

Cross-multiplying:

200v2 = 200v1

Dividing both sides by 200:

v2 = v1

Since we know that v1 = v2 - 10, we can substitute this into the equation:

v2 = (v2 - 10)

Simplifying:

v2 = v2 - 10

Bringing like terms together:

0 = -10

This equation has no solution. It means there is an error in the problem statement or the information provided.

Therefore, we cannot determine the speed of the second car based on the given information.