第44页 - 通城学典课时作业本八年级数学苏科版江苏专版

$ab$

$\frac{\sqrt{ab}}{b}$

$ \sqrt{b}$

能开得尽方

被开方数

分母

A

D

③

$\frac{\sqrt{7}}{7}$

$\frac{\sqrt{3}}{2}$

$ \begin{aligned}解：原式&=\frac {\sqrt5}{\sqrt{16}} \\ &=\frac {\sqrt5}4 \\ \end{aligned}$

$ \begin{aligned}解：原式&=\sqrt{\frac {10}3} \\ &=\frac {\sqrt{10}×\sqrt3}{\sqrt3×\sqrt3} \\ &=\frac {\sqrt{30}}3 \\ \end{aligned}$

$ \begin{aligned}解：原式&=-\frac {2×\sqrt6}{\sqrt6×\sqrt6} \\ &=-\frac {\sqrt6}3 \\ \end{aligned}$

$ \begin{aligned}解：原式&=\frac {\sqrt {20x^2y^2}}{\sqrt{z^5} } \\ &=\frac {2xy\sqrt {5}}{z^2\sqrt {z}} \\ &=\frac {2xy\sqrt {5z}}{z^3} \\ \end{aligned}$