Question

алгебра 7 класс срочно дам 10 балов ​

Answer 1

1)

$8x = 5x - 45$

$3x = - 45$

$x = - 15$

Ответ: - 15

2)

$\frac{5x + 72}{6} = \frac{3x + 72}{4}$

$20x + 288 = 18x + 432$

$2x = 144$

$x = 72$

Ответ: 72

3)

$23.8 {x}^{2} + 28.56x - 35.7x - 42.84 = 0$

$23.8 {x}^{2} - 7.14x - 42.84 = 0$

$d = { - 7.14}^{2} + 4 \times 23.8 \times 42.84 = 50.9796 + 4078.368 = 4129.3476$

$x1 = \frac{7.14 + 64.26}{47.6} = 1.5$

$x2 = \frac{7.14 - 64.26}{47.6} = - 1.2$

Ответ: - 1.2; 1.5