Question

Помогите решить пожалуйста!!!Число рядов в кинозале на 2 меньше, чем количество сидений в каждом ряду. Если увеличить число рядов в 3 раза, а количество сидений в каждом ряду уменьшить на 5, то количество сидений в зале увеличиться на 450. Сколько было сидений первоначально?

Answer 1

Ответ:

Решений нет.

Пошаговое объяснение:

чр=кс-2.

(чр*3)*(кс-5)=чр*кс+450.

чр*кс=?

Решение

3*чр*(кс-5)-чр*кс=450

3чр*кс-15чр-чр*кс=450

2чр(чр+2)-15чр=450

4х^2-11х-450=0

д=11*11+4*4*450=121+7200=7321=не является квадратом целого числа, значит и корни не будут целыми.

Answer 2

#### Problem Analysis To solve this problem, we need to determine the initial number of seats in the cinema hall. We are given two pieces of information: 1. The number of rows in the cinema hall is 2 less than the number of seats in each row. 2. If we increase the number of rows by 3 times and decrease the number of seats in each row by 5, the total number of seats in the hall will increase by 450. Let's assume that the initial number of seats in each row is 'x' and the initial number of rows is 'y'. #### Solution 1. From the first piece of information, we can write the equation: **y = x - 2**. 2. From the second piece of information, we can write the equation: **(3y)(x - 5) = xy + 450**. Now, let's solve these equations to find the initial number of seats in the cinema hall. #### Solving the Equations Substituting the value of 'y' from the first equation into the second equation, we get: **(3(x - 2))(x - 5) = x(x - 2) + 450** Expanding and simplifying the equation: **3x^2 - 21x + 30 = x^2 - 2x + 450** Bringing all terms to one side: **2x^2 - 19x + 420 = 0** Now, we can solve this quadratic equation to find the value of 'x' using the quadratic formula: **x = (-b ± √(b^2 - 4ac)) / (2a)** For this equation, a = 2, b = -19, and c = 420. Substituting these values into the quadratic formula: **x = (-(-19) ± √((-19)^2 - 4(2)(420))) / (2(2))** Simplifying further: **x = (19 ± √(361 - 3360)) / 4** **x = (19 ± √(-3000)) / 4** Since the value inside the square root is negative, the equation has no real solutions. Therefore, there is no valid solution for the initial number of seats in the cinema hall that satisfies both conditions given in the problem. #### Conclusion Based on the given information, there is no valid solution for the initial number of seats in the cinema hall.