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第134页

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$\frac{ab}{100}$

$ \begin{aligned}解：原式&=9\sqrt5÷\frac {\sqrt5}5×\frac 23×\sqrt{\frac 83} \\ &=9\sqrt5×\sqrt5×\frac 23×\frac {2\sqrt6}3 \\ &=20\sqrt6 \\ \end{aligned}$

$ \begin{aligned}解：原式&=(1÷\frac 25)×\sqrt{\frac {10}3÷\frac {7}3}×(-4\sqrt{\frac 75}) \\ &=\frac 52\sqrt{\frac {10}7}×(-4\sqrt{\frac 75}) \\ &=\frac 52×(-4)×\sqrt{\frac {10}7×\frac 75} \\ &=-10\sqrt2 \\ \end{aligned}$

$ \begin{aligned}解：原式&=(4x^2÷12×3)\sqrt{xy÷x^3×y} \\ &=x^2\sqrt{\frac {y^2}{x^2}} \\ &=xy \\ \end{aligned}$

$ \begin{aligned}解：原式&=[\frac 2b×(-\frac 32)÷3]×\sqrt{ab^5×a^3b÷\frac ba} \\ &=-\frac 1b×\sqrt{a^5b^5} \\ &=-a^2b\sqrt{ab} \\ \end{aligned}$

$ \begin{aligned}解：原式&=\sqrt5-\sqrt6-2\sqrt5+\frac {\sqrt6}3+\frac {3\sqrt5}5 \\ &=-\frac 25\sqrt5-\frac 23\sqrt6 \\ \end{aligned}$

$ \begin{aligned}解：原式&=2\sqrt{2ab}-b×\frac {\sqrt{2ab}}{b}-a×\frac {\sqrt{2ab}}{2a} \\ &=2\sqrt{2ab}-\sqrt{2ab}-\frac {\sqrt{2ab}}2 \\ &=\frac {\sqrt{2ab}}2 \\ \end{aligned}$

$ \begin{aligned}解：原式&=2\sqrt3-4×\frac {\sqrt2}4-2×\frac {\sqrt3}3+4×\frac {\sqrt2}2 \\ &=2\sqrt3-\sqrt2-\frac 23\sqrt3+2\sqrt2 \\ &=\sqrt2+\frac 43\sqrt3 \\ \end{aligned}$

$ \begin{aligned}解：原式&=\frac 23x×3\sqrt{x}-x^2×\frac {\sqrt{x}}x+3×\frac {x\sqrt{x}}4 \\ &=2x\sqrt{x}-x\sqrt{x}+\frac 34x\sqrt{x} \\ &=\frac 74x\sqrt{x} \\ \end{aligned}$