第134页 - 经纶学典学霸八年级数学上下册【江苏国标】

C

B

$\frac{7}{4}$

$2\sqrt {2}\ $

$a \sqrt{6a}$

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

1或4或16

$ \begin{aligned}解:原式&=\sqrt{6.5÷0.5} \\ &= \sqrt{6.5×2} \\ &=\sqrt {13} . \\ \end{aligned}$

$ \begin{aligned}解:原式&=\frac{\sqrt {45} }{\sqrt {5} } \\ &=\sqrt{\frac{45}{5}} \\ &=\sqrt {9} \\ &=3. \\ \end{aligned}$

$ \begin{aligned} 解:原式&=\sqrt {\frac {9}{2}}÷ (- \sqrt{\frac{8}{3}} ) \\ &=- \sqrt{\frac{9}{2}÷\frac {8}{3}} \\ &=- \sqrt{\frac {9}{2}×\frac{3}{8}}=- \frac{3\sqrt {3} }{4}. \\ \end{aligned}$

$ \begin{aligned}解:原式&=-\frac{2}{3} \sqrt{a^{3} b÷\frac {b}{a}} \\ &=- \frac{2}{3}\sqrt {a^{4} } \\ &=-\frac{2}{3}a^{2} . \\ \end{aligned}$

B

C