(√3-1)²-(2√3)²
=3-2√3+1-12
=-8-2√3

或者：
(√3-1)²-(2√3)²
=[(√3-1)+(2√3)]×[(√3-1)-(2√3)]
=[3√3-1]×[-√3-1]
=-9-3√3+√3+1
=-8-2√3