Question

Решите плиз последний номер 30 балов

Answer 1

A1.

$\frac{5a - 20c}{15ac} = \frac{5(a - 4c)}{15ac} = \frac{a - 4c}{3ac}$

Ответ: В.

А2.

$\frac{a}{ {a}^{2} - {c}^{2} } + \frac{c}{ {a}^{2} - {c}^{2} } = \frac{a + c}{ {a}^{2} - {c}^{2}} = \frac{a + c}{(a - c)(a + c)} = \frac{1}{a - c}$

Ответ: Б.

А3.

$\frac{5m}{n} - \frac{3m}{n} = \frac{5m - 3m}{n} = \frac{2m}{n}$

Ответ: А.

А4.

$\frac{x - 1}{3x - 12} - \frac{x - 3}{2x - 8} = \frac{x - 1}{3(x - 4)} - \frac{x - 3}{2(x - 4)} = \frac{2(x - 1) - 3(x - 3)}{6(x - 4)} = \frac{2x - 2 - 3x + 9}{6(x - 4)} = \frac{ 7 - x}{6(x - 4)}$

Ответ: Б.

А5.

$4a - \frac{8 {a}^{2} }{2a - 3} = \frac{4a}{1} - \frac{8 {a}^{2} }{2a - 3} = \frac{4a(2 a- 3) - 8 {a}^{2} }{2a - 3} = \frac{8 {a}^{2} - 12 a- 8 {a}^{2} }{2a - 3} = - \frac{12a}{2a - 3} = \frac{12a}{3 - 2a}$

Ответ: В.