因式分解:(1)1/2a²+ab+1/2b² (2)a²(x-y)+b²(y-x) (3)(x+y)²-4xy

问题描述:

因式分解:(1)1/2a²+ab+1/2b² (2)a²(x-y)+b²(y-x) (3)(x+y)²-4xy

(1)1/2a²+ab+1/2b² =1/2(a²+2ab+b²)=1/2(a+b)²(2)a²(x-y)+b²(y-x) =a²(x-y)-b²(x-y)=(x-y)(a²-b²)=(x-y)(a+b)(a-b)(3)(x+y)²-4xy=x²+2xy...