Question

6 класс математика уравнения
37. решите уравнения

Answer 1

B, C, D

Пошаговое объяснение:

1)

$\frac{1}{x} + \frac{1}{1 \frac{2}{3} x} = \frac{2}{5} \\ \frac{1}{x} + \frac{1}{ \frac{5}{3}x } = \frac{2}{5} \\ \frac{1}{x} + \frac{3}{5x} = \frac{2}{5} \\ \frac{5 + 3}{5x} = \frac{2}{5} \\ \frac{8}{5x} = \frac{2}{5} \\ 5x = \frac{8 \times 5}{2} = \frac{40}{2} = 20 \\ 5x = 20 \\ x = \frac{20}{5} = 4$

2)

$\frac{3}{1 \frac{1}{5}x } - \frac{1}{x} = 2 \frac{1}{2} \\ \frac{15}{6x} - \frac{1}{x} = \frac{1}{2} \\ \frac{15 - 6}{6x} = \frac{1}{2} \\ \frac{9}{6x} = \frac{1}{2} \\ 6x = \frac{9 \times 2}{1} = \frac{18}{1} \\ 6x = 18 \\ x = \frac{18}{6} \\ x = 3$

3)

$\frac{4}{1 \frac{1}{3}x } + \frac{1}{2x} = 0.7 \\ \frac{12}{4x} + \frac{1}{2x} = \frac{7}{10} \\ \frac{3}{x} + \frac{1}{2x} = \frac{7}{10} \\ \frac{6 + 1}{2x} = \frac{7}{10} \\ \frac{7}{2x} = \frac{7}{10} \\ 2x = \frac{7 \times 10}{7} = 10 \\ x = \frac{10}{2} \\ x = 5$