第136页 - 经纶学典新课时作业八年级数学上下册【江苏国标】

被开方数

化简

合并

C

$5\sqrt{3}$

$\frac{\sqrt{2}}{2}$

4

$20\sqrt{5}$

C

D

$ \begin{aligned}解:原式&=\sqrt{2x}+2\sqrt{2x}-3×3\sqrt{2x} \\ &=\sqrt{2x}+2\sqrt{2x}-9\sqrt{2x} \\ &=-6\sqrt{2x} \\ \end{aligned}$

$ \begin{aligned}解:原式&=3\sqrt{2}-2\sqrt{3}-\frac {\sqrt{2}}{4}+5\sqrt{3} \\ &=(3-\frac {1}{4})\sqrt{2}+(-2+5)\sqrt{3} \\ &=\frac {11}{4}\sqrt{2}+3\sqrt{3} \\ \end{aligned}$

（更多请点击查看作业精灵详解）

$ \begin{aligned}解:原式&=6\sqrt{2}-\frac {3\sqrt{2}}{2}+3\sqrt{2} \\ &=9\sqrt{2}-\frac {3\sqrt{2}}{2} \\ &=\frac {15\sqrt{2}}{2} \\ \end{aligned}$

$ \begin{aligned}解:原式&=4\sqrt{3}-2\sqrt{2}+\sqrt{2}-3\sqrt{3} \\ &=\sqrt{3}-\sqrt{2} \\ \end{aligned}$