原式
=2√3-√1/2-2/√3-1/√8+3√2
=2√3-√2/2-2√3/3-√2/4+3√2
=(2-2/3)√3+(-1/2-1/4+3)√2
=4√3/3+9√2/4在实数范围内分解因式x^4-4y^2，，哈哈则么写
x^4-4y^2
=(x^2)^2-(2y)^2
=(x^2+2y)(x^2-2y)