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第121页

信息发布者：

$\frac{1}{2}＜x≤7$

$\frac{ab}{10}$

解：原式$=\sqrt {\frac {n^2-\mathrm {m^2}}{\mathrm {m^2}n^2}}$

$=\frac {\sqrt {n^2-\mathrm {m^2}}}{mn}$

解：原式$=\frac {\sqrt {3a^3·6b^3}}{\sqrt {2ab}}$

$=\frac {\sqrt {18a^3b^3}}{\sqrt {2ab}}$

$=\sqrt {\frac {18a^3b^3}{2ab}}$

$=\sqrt {9a^2b^2}$

$=3ab$

解：原式$=-\frac {4}{5}\sqrt {5÷\frac {9}{5}}$

$=-\frac {4}{5}\sqrt {5×\frac {5}{9}}$

$=-\frac {4}{5}×\frac {5}{3}$

$=-\frac {4}{3}$

解：原式$=\frac {2\sqrt {2}×2\sqrt {3}}{4}÷\sqrt {6}$

$=\frac {4\sqrt {6}}{4}÷\sqrt {6}$

$=\sqrt {6}÷\sqrt {6}$

$=1$

解：原式$=\frac {3}{5}×(-\frac {15}{4})×(-\frac {5}{6})×\sqrt {xy^5÷\frac {y}{x}× x^3y}$

$ =\frac {15}{8}×\sqrt {x^5y^5}$

$ =\frac {15}{8}x^2y^2\sqrt {xy}$