Đáp án:
`1)(5+sqrt5)/(5-sqrt5)+(5-sqrt5)/(5+sqrt5)`
`=(5+sqrt5)^2/(25-5)+(5-sqrt5)^2/(25-5)`
`=((5+sqrt5)^2+(5-sqrt5)^2)/20`
`=(30+10sqrt5+30-10sqrt5)/20`
`=60/20=3`
`2)1/(2sqrt5+3sqrt2)-1/(2sqrt5-3sqrt2)`
`=(2sqrt5-3sqrt2)/(20-18)-(2sqrt5+3sqrt2)/(20-18)`
`=(2sqrt5-3sqrt2-2sqrt5-3sqrt2)/2`
`=-3sqrt2`