把下列各式分解因式: (1)1/2a2+ab+1/2b2; (2)(x-y)(x-3y)+y2.
问题描述:
把下列各式分解因式:
(1)
a2+ab+1 2
b2; 1 2
(2)(x-y)(x-3y)+y2.
答
(1)原式=
(a2+2ab+b2)1 2
=
(a+b)2;1 2
(2)原式=x2-3xy-xy+3y2+y2=x2-4xy+4y2
=(x-2y)2.