.Rút gọn B=Căn(1-căn5)^2+$\sqrt{6+2căn5}$

`B=\sqrt[(1-sqrt5)^2]+\sqrt(6+2\sqrt5)`

`B=|1-\sqrt5|+\sqrt(5+2\sqrt5+1)`

`B=\sqrt5-1+\sqrt[(\sqrt5+1)^2]`

`B=\sqrt5-1+|\sqrt5+1|`

`B=\sqrt5-1+\sqrt5+1`

`B=2\sqrt5`