Đáp án: `sqrt5`
Giải thích các bước giải:
`(5+sqrt5)/(sqrt5+2)+(sqrt5)/(sqrt5-1)-(3sqrt5)/(3+sqrt5)`
`=((5+sqrt5)(sqrt5-2))/((sqrt5+2)(sqrt5-2))+(sqrt5(sqrt5+1))/((sqrt5-1)(sqrt5+1))-(3sqrt5(3-sqrt5))/((3+sqrt5)(3-sqrt5))`
`=3sqrt5+(5+sqrt5)/4-(9sqrt5-15)/4`
`=3sqrt5-5+(5+sqrt5-9sqrt5+15)/4`
`=3sqrt5-5+5-2sqrt5`
`=sqrt5`