第143页 - 亮点给力提优课时作业本八年级数学江苏版

C

D

C

$\sqrt {3}$

$5 \sqrt {S}$

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

$=2+\sqrt {2}$

$=4\sqrt {5}-3\sqrt {5}-2\sqrt {3}+2\sqrt {3}$

$=\sqrt {5}$

$= \sqrt {5x}+ \sqrt {5x}-\frac {\sqrt {5x}}{2}$

$=\frac {3\sqrt {5x}}{2}$

$=2\sqrt {6}+\frac {\sqrt {2}}{2}-\frac {\sqrt {2}}{4}+\sqrt {6}$

$=3\sqrt {6}+\frac {\sqrt {2}}{4}$

B

$\frac {21}{4}$