Ответ:

Решение:

а) Подставим значения \( a = \frac{1}{2} \) и \( b = \frac{1}{4} \) в дробь:

\[ \frac{6\left(\frac{1}{2}\right)^2 - 3\left(\frac{1}{2}\right)\left(\frac{1}{4}\right)}{8\left(\frac{1}{2}\right)\left(\frac{1}{4}\right) - 4\left(\frac{1}{4}\right)^2} = \frac{6\cdot\frac{1}{4} - \frac{3}{8}}{\frac{8}{8} - 4\cdot\frac{1}{16}} = \frac{\frac{6}{4} - \frac{3}{8}}{1 - \frac{4}{16}} = \frac{\frac{3}{2} - \frac{3}{8}}{1 - \frac{1}{4}} = \frac{\frac{12-3}{8}}{\frac{3}{4}} = \frac{\frac{9}{8}}{\frac{3}{4}} = \frac{9}{8} \cdot \frac{4}{3} = \frac{3}{2} \cdot \frac{1}{1} = \frac{3}{2} \]

б) Упростим дробь, вынеся общие множители:

\[ \frac{x^5+1}{x^3+x} = \frac{x^5+1}{x(x^2+1)} \]

При \( x = 0,1 = \frac{1}{10} \):

\[ \frac{\left(\frac{1}{10}\right)^5 + 1}{\frac{1}{10}\left(\left(\frac{1}{10}\right)^2+1\right)} = \frac{\frac{1}{100000} + 1}{\frac{1}{10}\left(\frac{1}{100}+1\right)} = \frac{\frac{100001}{100000}}{\frac{1}{10}\left(\frac{101}{100}\right)} = \frac{\frac{100001}{100000}}{\frac{101}{1000}} = \frac{100001}{100000} \cdot \frac{1000}{101} = \frac{100001}{100 \cdot 101} = \frac{100001}{10100} \approx 9.9 \]

При \( x = -\frac{1}{3} \):

\[ \frac{\left(-\frac{1}{3}\right)^5 + 1}{-\frac{1}{3}\left(\left(-\frac{1}{3}\right)^2+1\right)} = \frac{-\frac{1}{243} + 1}{-\frac{1}{3}\left(\frac{1}{9}+1\right)} = \frac{\frac{242}{243}}{-\frac{1}{3}\left(\frac{10}{9}\right)} = \frac{\frac{242}{243}}{-\frac{10}{27}} = \frac{242}{243} \cdot \left(-\frac{27}{10}\right) = \frac{242}{9} \cdot \left(-\frac{1}{10}\right) = -\frac{242}{90} = -\frac{121}{45} \]

Ответ: а) \(\frac{3}{2}\); б) \(\frac{100001}{10100}\) при \( x = 0,1 \), \(-\frac{121}{45}\) при \( x = -\frac{1}{3} \).