（5-√3）^2
=25+3+2根号3
=28+2根号3
(1+√3)(2-√3)
=2-√3+2√3-3
=√3-1
√50-4√2分之1+2√8
=√5²*2-2√2+2*2√2
=5√2+2√2
=7√2
3√12-4√3分之1-2√27
=3√2²*3-4/3√3-2√3²*3
=6√3-4/3√3-6√3
=-4/3√3