Hướng dẫn trả lời:
$\text{a) $\sqrt{32}$ - $3\sqrt{50}$ + $2\sqrt{8}$.}$
$\text{= $4\sqrt{2}$ - $15\sqrt{2}$ + $4\sqrt{2}$.}$
$\text{= $-7\sqrt{2}$.}$
$\text{b) $(\sqrt{7} - \sqrt{5})^2$ + $\sqrt{140}$.}$
$\text{= (7 - 2$\sqrt{35}$ + 5) + $2\sqrt{35}$.}$
$\text{= (12 - 2$\sqrt{35}$) + $2\sqrt{35}$.}$
$\text{= 12 - 2$\sqrt{35}$ + $2\sqrt{35}$.}$
$\text{= 12.}$
Đáp án:
$\text{a) $-7\sqrt{2}$.}$
$\text{b) 12.}$
