解
(2√3-√6)²
=(2√3)²-2×2√3×√6+(√6)²
=12-12√2+6
=18-12√22根号8-9根号1/22√8-9√1/2
=4√2-9×(√2/2)
=8√2/2-9√2/2
=-√2/2