原式1=(x-4+5-2x)(x-4-5+2x) (平方差公式)=(1-x)(3x-9)=3(1-x)(x-3)=0x1=1 x2=3原式2=(x-3)[5x-(x+1)] (移项合并同类项）=(x-3)(4x-1)=0x1=3 x2=1/4原式3=x²+x-6=-6x²+x=0x(x+1)=0x1=0 x2=-1原式4=(3x-1+2...