Question

2) 2,4 + (х : 3 – 5) = 4; 3) 2,45 : (2х – 1,4) = 3,5.

Answer 1

2) раскроем скобки

12/5 + (1/3)x - 5 = 4

-13/5 + (1/3)x = 4, домножим обе части на 15

15 (-13/5 + (1/3)х) = 15 * 4

-15 * 13/5 + 15 * (1/3)х = 60

-3 * 13 + 5х = 60

-39 + 5х = 60

5х = 60 + 39

5х = 99

х = 99/5 = 19 целых 4/5 = 19,8

ответ: 19,8

3) область допустимых значений: 2х-1,4 не должно быть равно 0, то есть х не равен 0,7

49/20 : (2х - 7/5) = 3,5

49/20 : (10х-7)/5 = 3,5

49/20 * 5/(10х-7) = 3,5

49/4 * 1/(10х-7) = 3,5

49/4(10х-7) = 3,5, домножим обе части на знаменатель 4(10х-7), он не равен 0, ибо на 0 делить нельзя

49 = 3,5 * 4(10х-7)

49 = 14(10 х-7)

49 = 140х - 98

-140х = -98 - 49

-140х = -147

х = 147/140 = 21/20 = 1 целая 1/20 = 1,05

ответ: 1,05

Answer 2

To solve these equations, let's start with the first one:

$2.4 + \left(\frac{x}{3} - 5\right) = 4$

First, simplify the equation inside the parentheses:

$\frac{x}{3} - 5 = 4 - 2.4$ $\frac{x}{3} - 5 = 1.6$

Next, add 5 to both sides to isolate $\frac{x}{3}$:

$\frac{x}{3} = 6.6$

Multiply both sides by 3 to solve for $x$:

$x = 19.8$

Now, let's move on to the second equation:

$2.45 : (2x - 1.4) = 3.5$

First, multiply both sides by $(2x - 1.4)$ to get rid of the denominator:

$2.45 = 3.5(2x - 1.4)$

Now, distribute 3.5 on the right side:

$2.45 = 7x - 4.9$

Add 4.9 to both sides:

$7x = 7.35$

Divide by 7:

$x = 1.05$

So the solutions to the given equations are $x = 19.8$ for the first equation and $x = 1.05$ for the second equation.