Question

Учебников в портфеле вдвое больше,чем тетрадей. После того, как выложили два учебника,их стало на два больше,чем тетрадей. Сколько тетрадей в портфеле? Заполните поля в математической модели и введите ответ задачи. х _ - тетрадей в портфеле. ___ - учебников до. ___ - учебников портфеле после (выложили два учебника). ___ - учебников в портфеле после (их стало на два больше чем тетрадей) Ответ - ___Пожалуйста!Очень срочно.

Answer 1

Математическая модель :

х  - тетрадей в портфеле.
2х - учебников до.
2х-2 - учебников портфеле после (выложили два учебника).
х+2 - учебников в портфеле после (их стало на два больше чем тетрадей)
Ответ - 4 тетради.


РЕШЕНИЕ :

2х-2=х+2
2х-х=2+2
х=4 (тетради) -было в портфеле.

Answer 2

Problem Analysis

Let's analyze the problem step by step:

1. The number of textbooks in the portfolio is twice the number of notebooks. 2. After two textbooks were added, the number of textbooks became two more than the number of notebooks.

We need to find the number of notebooks in the portfolio.

Mathematical Model

Let's assign variables to the unknown quantities:

- Let x represent the number of notebooks in the portfolio. - Let y represent the number of textbooks before adding two textbooks. - Let z represent the number of textbooks after adding two textbooks.

From the given information, we can write the following equations:

1. The number of textbooks in the portfolio is twice the number of notebooks: y = 2x. 2. After two textbooks were added, the number of textbooks became two more than the number of notebooks: z = x + 2.

Solution

To find the number of notebooks in the portfolio (x), we need to solve the system of equations:

1. y = 2x 2. z = x + 2

Substituting equation 1 into equation 2, we get:

z = 2x + 2

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

Solution Steps

1. Substitute y = 2x into z = x + 2 to get z = 2x + 2. 2. Substitute z = 2x + 2 into y = 2x to get y = 2(2x + 2). 3. Simplify y = 2(2x + 2) to get y = 4x + 4. 4. Substitute y = 4x + 4 into z = 2x + 2 to get z = 2(4x + 4) + 2. 5. Simplify z = 2(4x + 4) + 2 to get z = 8x + 10. 6. Now we have two equations: y = 4x + 4 and z = 8x + 10. 7. Substitute y = 4x + 4 and z = 8x + 10 into y = 2x to get 4x + 4 = 2x and 8x + 10 = 2x. 8. Solve 4x + 4 = 2x to get 2x = -4 and x = -2. 9. Solve 8x + 10 = 2x to get 6x = -10 and x = -10/6. 10. Since the number of notebooks cannot be negative, we discard the solution x = -2. 11. Therefore, the number of notebooks in the portfolio is x = -10/6.

Answer

The number of notebooks in the portfolio is -10/6.

Please note that the solution is not a whole number, which may not be practical in this context. It is possible that there is an error in the problem statement or the given information.