\[\frac{1,6a^{7}}{b^{3}}\sqrt{\frac{b^{22}}{0,64a^{4}}},\ если\ b > 0\]
\[\frac{1,6a^{7}}{b^{3}}\sqrt{\frac{b^{22}}{0,64a^{4}}} = \frac{1,6a^{7} \cdot b^{11}}{b^{3} \cdot 0,8a^{2}} =\]
\[= 2a^{5}b^{8}\]