Решебник по алгебре 8 класс Мерзляк ФГОС Задание 86

\[\boxed{\text{8}\text{6}\text{\ (86).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)\ \frac{4a - b}{a} = \frac{4a}{a} - \frac{b}{a} = 4 - \frac{b}{a}\]

\[2)\ \frac{b^{2} + 7b + 3}{b + 7} = \frac{b^{2} + 7b}{b + 7} +\]

\[+ \frac{3}{b + 7} = \frac{b(b + 7)}{(b + 7)} + \frac{3}{b + 7} =\]

\[= b + \frac{3}{b + 7}\]

\[\boxed{\text{86.\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[\frac{a}{b} = - 2;\]

\[\frac{b}{a} = - \frac{1}{2}.\]

\[1)\ \frac{a - b}{a} = \frac{a}{a} - \frac{b}{a} = 1 - \frac{b}{a} =\]

\[= 1 + \frac{1}{2} = 1,5\]

\[2)\ \frac{4a + 5b}{b} = \frac{4a}{b} + \frac{5b}{b} =\]

\[= 4 \cdot \frac{a}{b} + 5 = 4 \cdot ( - 2) + 5 =\]

\[= - 8 + 5 = - 3\]

\[3)\ \frac{a^{2} - 2ab + b^{2}}{\text{ab}} =\]

\[= \frac{a^{2}}{\text{ab}} - \frac{2ab}{\text{ab}} + \frac{b^{2}}{\text{ab}} = \frac{a}{b} - 2 + \frac{b}{a} =\]

\[= - 2 - 2 - \frac{1}{2} = - 4,5\]