`@Mon`
`A=(3-\sqrt{5})\sqrt{3+\sqrt{5}}+(3+\sqrt{5})\sqrt{3-\sqrt{5}}`
`<=>A^2=(3-\sqrt{5})^2(3+\sqrt{5})+(3+\sqrt{5})^2(3-\sqrt{5})+2(3-\sqrt{5})(3+\sqrt{5})\sqrt{(3+\sqrt{5})(3-\sqrt{5})}`
`=12-4\sqrt{5}+12+4\sqrt{5}+8\sqrt{4}`
`=24+16-40`
`=>A=\sqrt{40}=2\sqrt{10}`
`Vậy` `A=(3-\sqrt{5})\sqrt{3+\sqrt{5}}+(3+\sqrt{5})\sqrt{3-\sqrt{5}}=2\sqrt{10}`
