(√6 + 2)^2 _(√6 _2)^2

Surd?

If you mean -----

(√6 + 2)^2 - (√6 - 2)^2
then we get
6 + 4√6 + 4 - (6 - 4√6 + 4)
= 10 + 4√6 - 10 + 4√6
= 8√6

do you see a surd?