8.17. Вычислите: а) ((1/25)^(−1/2) · 7^(−1) − (1/8)^(−1/3) · 2^(−3)) : 49^(−1/2); б) (8^(−1/3) · 25^(−1/2) − 2^(−1)) / (64^(1/4) · 2^(1/2)).

1. \(\left(\left(\frac1{25}\right)^{-1/2}·7^{-1}-\left(\frac18\right)^{-1/3}·2^{-3}\right):49^{-1/2}=\left(5·\frac17-2·\frac18\right):\frac17=\left(\frac57-\frac14\right)·7=\frac{13}{28}·7=\frac{13}{4}\).
2. \(\frac{8^{-1/3}·25^{-1/2}-2^{-1}}{64^{1/4}·2^{1/2}}=\frac{\frac12·\frac15-\frac12}{(2\sqrt2)·\sqrt2}=\frac{-\frac25}{4}=-\frac1{10}\).

Ответ: а) \(\frac{13}{4}\); б) \(-\frac1{10}\).