﹙√5＋1﹚﹙√5－1﹚
=(√5)²－1²
=5-1
=4
﹙2－√7﹚﹙2＋√7﹚
=2²-(√7)²
=4-7
=-3
﹙2√3＋1﹚²
=(2√3)²+4√3+1
=12+4√3+1
=13+4√3
√3－√2/√3＋√2
=(√3－√2)²/[(√3＋√2)(√3－√2)]
=(3－2√6+2)²/[(√3)²-(√2)²]
=5－2√6