Question

Алгебра. 7 класс. Помогите решить.

Answer 1

Смотри.......................

Answer 2

Объяснение:

1

$\frac{18}{81} - \frac{20}{9} = \frac{2}{9} (1 - 10) = - 2$

2

$\frac{7}{a(1 - a)} - \frac{7}{a} = \frac{7}{a} ( \frac{1}{1 - a} - 1) = \frac{7}{a} \frac{1 - 1 - + a}{1 - a} = \frac{7}{1 - a} = - \frac{1}{5} = - 0.2$

3

$\frac{6.8 - 4.7}{1.4} = \frac{2.1}{1.4} = \frac{0.3}{0.2} = \frac{3 \times 10}{10 \times 2} = \frac{3}{2} = 1.5$

4

$- 1 - 3x = 2x + 1 \\ 5x = - 2 \\ x = - \frac{2}{5} = - 0.4$