`Đáp` `án:`
`D. 1/(\sqrt{5}-\sqrt{3})-1/(\sqrt{5}+\sqrt{3})`
`= (\sqrt{5}+\sqrt{3}-\sqrt{5}+\sqrt{3})/((\sqrt{5}+\sqrt{3})(\sqrt{5}-\sqrt{3})`
`= (2\sqrt{3})/(5-3)`
`= (2\sqrt{3})/2`
`= \sqrt{3}`
`E. (\sqrt{3}+\sqrt{2})/(\sqrt{3}-\sqrt{2})-(\sqrt{3}-\sqrt{2})/(\sqrt{3}+\sqrt{2})`
`= ((\sqrt{3}+\sqrt{2})^2-(\sqrt{3}-\sqrt{2})^2)/((\sqrt{3}-\sqrt{2})(\sqrt{3}+\sqrt{2}))`
`= ((\sqrt{3}+\sqrt{2}-\sqrt{3}+\sqrt{2})(\sqrt{3}+\sqrt{2}+\sqrt{3}-\sqrt{2}))/(3-2)`
`= (2\sqrt{2}.2\sqrt{3})/1`
`= 4\sqrt{6}`
`H. 6\sqrt{3/4}+20\sqrt{18/25}-15\sqrt{25/3}+18\sqrt{4/3}`
`= 3\sqrt{3}+12\sqrt{2}-25\sqrt{3}+12\sqrt{3}`
`= 12\sqrt{2}-10\sqrt{3}`
`text{~ Học Tốt Nha ~}`
