$\text{a)}x={\left(6\frac{1}{4}\right)}^{0,5}\cdot {100}^{-0,5}={\left(\frac{25}{4}\right)}^{0,5}\cdot {\left(\frac{1}{100}\right)}^{0,5}=\sqrt{\frac{25}{4}}\cdot \sqrt{\frac{1}{100}}=\frac{5}{2}\cdot \frac{1}{10}=\frac{1}{4}$  

Liczba odwrotna do x to