Свойства степеней

$$\frac{16a^{12}}{2a^{11}} = 8a = 8 \cdot 11 = 88$$

$$b^{\frac{1}{5}} \cdot b^{\frac{9}{5}} = b^{2} = 7^2 = 49$$

$$7^{2x-1} : 7^{2x} : x = 7^{-1} : x = \frac{1}{7} \cdot 14 = 2$$

$$\dfrac{a^{7,4}}{a^{8,4}} = a^{7,4-8,4} = a^{-1} = \dfrac{1}{a} = \dfrac{1}{0,4} = 2,5$$

$$\frac{a^{1/9} \cdot a^{1/18}}{a \cdot a^{1/6}} = \frac{a^{\frac{1}{9}+\frac{1}{18}}}{a^{1+\frac{1}{6}}} = \frac{a^{\frac{1}{6}}}{a^{\frac{7}{6}}} = a^{\frac{1}{6}-\frac{7}{6}} = a^{-1} = \dfrac{1}{a} = \dfrac{1}{1,25} = 0,8$$