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

(1)3x-12x3=3x(1-4x2)=3x(1-2x)(1+2x);
                
(2)-2a3+12a2-18a
=-2a(a2-6a+9)
=-2a(a-3)2
(3)(x+y)2+2(x+y)+1=(x+y+1)2