分解因式: (1)5x2-15x+2xy-6y (2)3a3b-81b4 (3)-a4+16.
问题描述:
分解因式:
(1)5x2-15x+2xy-6y
(2)3a3b-81b4
(3)-a4+16.
答
(1)原式=5x(x-3)+2y(x-3)=(x-3)(5x+2y),
(2)原式=3b[a3-(3b)3]=3b(a-3b)(a2+9b2-3ab).
(3)原式=-(a4-24)=-(a2+4)(a-2)(a+2).