Đáp án:
`\sqrt{(2-sqrt3)/(2+sqrt3)}+sqrt{(2+sqrt3)/(2-sqrt3)}`
`=\sqrt{(4-2sqrt3)/(4+2sqrt3)}+sqrt{(4+2sqrt3)/(4-2sqrt3)}`
`=sqrt{(3-2sqrt3+1)/(3+2sqrt3+1)}+sqrt{(3+2sqrt3+1)/(3-2sqrt3+1)}`
`=sqrt{(sqrt3-1)^2/(sqrt3+1)^2}+sqrt{(sqrt3+1)^2/(sqrt3-1)^2}`
`=|(sqrt3-1)/(sqrt3+1)|+|(sqrt3+1)/(sqrt3-1)|`
`=(sqrt3-1)/(sqrt3+1)+(sqrt3+1)/(sqrt3-1)`
`=((sqrt3-1)^2)/((sqrt3+1)(sqrt3-1))+((sqrt3+1)^2)/((sqrt3-1)(sqrt3+1))`
`=(sqrt3-1)^2/2+(sqrt3+1)^2/2`
`=((sqrt3-1)^2+(sqrt3+1)^2)/2`
`=(3-2sqrt3+1+3+2sqrt3+1)/2`
`=8/2=4`
