`8A)`
`b)` `\sqrt{frac{3-\sqrt{5}}{3+\sqrt{5}}}`
`=\sqrt{frac{(3-\sqrt{5})(3-\sqrt{5})}{(3+\sqrt{5})(3-\sqrt{5})}}`
`=\sqrt{frac{(3-\sqrt{5})^2}{9-5}}`
`=frac{\sqrt{(3-\sqrt{5})^2}}{\sqrt{4}}`
`=frac{|3-\sqrt{5}|}{2}`
`=frac{3-\sqrt{5}}{2}` (do `3-\sqrt{5}>0)`
`8B)`
`b)` `\sqrt{frac{2-\sqrt{3}}{2+\sqrt{3}}}`
`=\sqrt{frac{(2-\sqrt{3})(2-\sqrt{3})}{(2+\sqrt{3})(2-\sqrt{3})}}`
`=\sqrt{frac{(2-\sqrt{3})^2}{4-3}}`
`=frac{\sqrt{(2-\sqrt{3})^2}}{\sqrt{1}}`
`=frac{|2-\sqrt{3}|}{1}`
`=2-\sqrt{3}` (do `2-\sqrt{3}>0)`
