(√2+√3-√6)²-(√2-√3+√6)²
=(√2+√3-√6+√2-√3+√6)(√2+√3-√6-√2+√3-√6)
=2√2*(2√3-2√6)
=4√6-8√3
求x²+3x-1
=(√2-1)²+3(√2-1)-1
=2-2√2+1+3√2-3-1
=√2-1