8. 若矩形的长和宽分别为$\boldsymbol{\sqrt{125}}$和$\boldsymbol{\sqrt{20}}$,则其周长为.

8. $14\sqrt{5}$

9. 计算:
(1)$\boldsymbol{\sqrt{8}-(3\sqrt{32}+2\sqrt{18})}$;
(2)$\boldsymbol{\dfrac{1}{2}\sqrt{24}-( 6\sqrt{\dfrac{1}{6}}+\sqrt{3})}$;

(3)$\boldsymbol{\sqrt{0.5}-8×\dfrac{1}{\sqrt{8}}}$;
(4)$\boldsymbol{|2-\sqrt{3}|+|1-\sqrt{3}|}$;
(5)$\boldsymbol{\sqrt{0.2}-\dfrac{1}{2}\sqrt{20}-( \sqrt{\dfrac{5}{4}}-\sqrt{0.45}+\sqrt{90})}$.

9.(1)$-16\sqrt{2}$ (2)$-\sqrt{3}$ (3)$-\dfrac{3}{2}\sqrt{2}$ (4)1 (5)$-\sqrt{5}-3\sqrt{10}$

10. 已知$\boldsymbol{2\sqrt{7}}$与$\boldsymbol{5\sqrt{5}}$是等腰$\boldsymbol{△ ABC}$的两边的长,求$\boldsymbol{△ ABC}$的周长.

10. $2\sqrt{7}+10\sqrt{5}$