Question

отдаю все баллы Алгебра ​

Answer 1

Ответ:

2. 1)

$\frac{5}{x} - \frac{x + 5}{x - 3}$

$\frac{5(x - 3) - x(x + 5)}{x(x - 3)}$

$\frac{5x - 15 - {x}^{2} - 5x }{x(x - 3)}$

$\frac{ - 15 - {x}^{2} }{x(x - 3)}$

$\frac{15 - {x}^{2} }{ {x }^{2} - 3x }$

$\frac{15}{ - 3x}$

$- \frac{5}{x}$

2)

$\frac{2 {a}^{2} }{ {a}^{2} - 4 } - \frac{2a}{a + 2}$

$\frac{2 {a}^{2} }{(a - 2) \times (a + 2)} - \frac{2a}{a + 2}$

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

$\frac{2 {a}^{2} - 2 {a}^{2} + 4a }{ {a}^{2} - 4}$

$\frac{4a}{ {a}^{2} - 4 }$

3.

$\frac{ {x}^{2} - 4x + 4 }{ {x}^{2} - 4 } \div \frac{10x - 20}{ {x}^{2} + 2x }$

$\frac{ {80}^{2} - 4 \times 80 + 4 }{ {80}^{2} - 4 } \div \frac{10 \times 80 - 20}{ {80}^{2} + 2 \times 80 }$

$\frac{6400 - 320 + 4}{6400 - 4} \div \frac{800 - 20}{6400 + 160}$

$\frac{39}{41} \div \frac{39}{328}$

$\frac{39}{41} \times \frac{328}{39}$

$8$

4.

$\frac{x}{y} = a$

$\frac{y}{z } = \frac{1}{a}$

$\frac{x}{y} \times \frac{y}{z} = \frac{x}{z} = a \times \frac{1}{a} = 1$