Question

Алгебра 8 класс (не срочно)

Answer 1

1.

$\frac{5}{n^5} + \frac{4 - 5n^2}{n^7} = \frac{5}{n^5} + \frac{4}{n^7} - \frac{5n^2}{n^7} =$

$= \frac{5}{n^5} + \frac{4}{n^7} - \frac{5}{n^5} = \frac{4}{n^7}$

2.

$\frac{a-2b}{ab^2} + \frac{2a-b}{a^2b} = \frac{a\cdot(a-2b)}{a^2b^2} + \frac{b\cdot(2a-b)}{a^2b^2} =$

$= \frac{a^2 - 2ab + 2ab - b^2}{a^2b^2} = \frac{a^2 - b^2}{a^2b^2} =$

$= \frac{a^2}{a^2b^2} - \frac{b^2}{a^2b^2} = \frac{1}{b^2} - \frac{1}{a^2}$

3.

$\frac{3}{b} + \frac{4}{b+2} = \frac{3\cdot(b+2)}{b\cdot(b+2)} + \frac{4\cdot b}{b\cdot(b+2)} =$

$= \frac{3b + 6 + 4b}{b^2+2b} = \frac{7b+6}{b^2+2b}$