把下列各式因式分解: (1)3x-12x3 (2)-2a3+12a2-18a (3)9a2(x-y)+4b2(y-x) (4)(x+y)2+2(x+y)+1.

问题描述:

把下列各式因式分解:
(1)3x-12x3
(2)-2a3+12a2-18a
(3)9a2(x-y)+4b2(y-x)          
(4)(x+y)2+2(x+y)+1.

(1)原式=3x(1-4x2)=3x(1+2x)(1-2x);
(2)原式=-2a(a2-6a+9)=-2a(a-3)2
(3)原式=9a2(x-y)-4b2(x-y)=(x-y)(9a2-4b2)=(x-y)(3a+2b)(3a-2b).
(4)原式=(x+y+1)2