1.3x²－9=0
3x²=9
x²=3
x=±√3
2.3x²－7x＋4=0
(3x-4)(x-1)=0
x=4/3或x=1
3.﹙x＋3﹚﹙x＋1﹚=6x＋4
x²+4x+3-6x-4=0
x²-2x=1
(x-1)²=2
x-1=±√2
x=1±√2
4.﹙2x－1﹚²=x²＋4x＋4
(2x-1)²=(x+2)²
(2x-1+x+2)(2x-1-x-2)=0
(3x+1)(x-3)=0
x=-1/3或x=3