tính a+b giúp em với ạ

Ta có: `a^2+b^2 = 4+sqrt(10+2sqrt5)+4-sqrt(10+2sqrt5)`

`=>` `a^2+b^2=8`

`=>` `(a+b)^2 - 2ab = 8`

`=>` `(a+b)^2 - 2sqrt((4+sqrt(10+2sqrt5))(4-sqrt(10+2sqrt5)))=8`

`=>` `(a+b)^2-2sqrt(6-2sqrt5)=8`

`=>` `(a+b)^2 = 8+2sqrt(6-2sqrt5)`

`=8+2sqrt(5-2sqrt5+1)`

`=8+2sqrt((sqrt5-1)^2)`

`=8+2abs(sqrt5-1)`

`=8+2(sqrt5-1)`

`=8+2sqrt5-2`

`=6+2sqrt5`

`=>` `a+b=sqrt(6+2sqrt5)`

`=sqrt(5+2sqrt5+1)`

`=sqrt((sqrt5+1)^2)`

`=abs(sqrt5+1)`

`=sqrt5+1`

Vậy `a+b=sqrt5+1`