20a^4-33a^2b^2+7b^4
=(4a^2-b^2)(5a^2-7b^2)
=(2a+b)(2a-b)(5a^2-7b^2)
x²－5x＋3＝x²－5x＋﹙5/2﹚²－﹙5/2﹚²＋3
＝﹙x－5/2﹚²－13/4
＝﹙x－5/2－√13/2﹚﹙x－5/2＋√13/2﹚
x^2-2√2*x-3
=(x^2-2√2x+2)-2-3
=(x-√2)^2-5
=(x-√2+√5)(x-√2-√5)在實(shí)數(shù)范圍內(nèi)分解因式：1、3x^2+4xy-y^22、（x^2-2x)^2-7(x^2-2x)+12分解因式：x^2+x-(a^2-a)3x2+4xy-y2=3(x2+ xy×4/3 - y2×1/3)=3[(x2+ 2×2/3 ×xy +4/9y2) - y2/3- 4/9y2]=3[(x+2/3y)2 - 7/9 y2] =3(x+2/3y +√7/3y)(x+2/3y - √7/3y)=3[x+(2+√7)/3y][x+(2-√7)/3y](x^2-2x)^2-7(x^2-2x)+12=(x^2-2x-4)(x^2-2x-3)=(x^2-2x-4)(x-3)(x+1)x^2+x-(a^2-a)=x^2+x-a^2+a=x^2-a^2+(x+a)=(x+a)(x-a)+(x+a)=(x-a+1)(x+a)