Question

9 і 10 завдання будь ласка

Answer 1

9)

$\displaystyle \sqrt{5b^2}=|b|*\sqrt{5}$

т.к. b≤0, то

$\displaystyle |b|*\sqrt{5}=-b\sqrt{5}$

10)

$\displaystyle \frac{\sqrt{6}-\sqrt{2}}{\sqrt{3}-1}=\frac{(\sqrt{6}-\sqrt{2})(\sqrt{3}+1)}{(\sqrt{3}-1)(\sqrt{3}+1)}=\frac{\sqrt{18}-\sqrt{6}+\sqrt{6}-\sqrt{2}}{(\sqrt{3})^2-1}=\\\\=\frac{\sqrt{9*2}-\sqrt{2}}{2}=\frac{3\sqrt{2}-\sqrt{2}}{2}=\sqrt{2}$

$\displaystyle \frac{\sqrt{a}+1}{a-1}=\frac{\sqrt{a}+1}{\sqrt{a}^2-1}=\frac{\sqrt{a}+1}{(\sqrt{a}-1)(\sqrt{a}+1)}=\frac{1}{\sqrt{a}-1}$