第119页 - 江苏版实验班提优训练数学八年级上下册答案

B

C

A

C

$\frac{1}{2} $

2

$解:原式=2\sqrt{3}+3\sqrt{3}+(\sqrt{3}-1)$

$=2\sqrt{3}+3\sqrt{3}+\sqrt {3} -1$

$=6\sqrt {3} -1.$

C

2

-1

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

$解:原式=3-1-(3+2\sqrt{3}+1)\ $

$=3-1-3-2\sqrt{3}-1$

$=-2-2\sqrt{3}.$

$ \begin{aligned}解:原式&= \sqrt{\frac{1}{2}}+\frac{2\sqrt{6}}{3}+2\sqrt{6}- \sqrt{\frac{1}{8}} \\ &=\frac{\sqrt{2}}{2}+\frac{2\sqrt{6}}{3}+2\sqrt{6}-\frac{\sqrt{2}}{4} \\ &=\frac{\sqrt{2}}{4}+\frac{8\sqrt{6}}{3} \\ \end{aligned}$