(x-y)(x²+xy+y²);(x+y-1)²;(a+1/2)²

问题描述:

(x-y)(x²+xy+y²);(x+y-1)²;(a+1/2)²

(x-y)(x²+xy+y²)=x^3-y^3
(x+y-1)²
=(x+y)^2-2(x+y)+1
=x^2+2xy+y^2-2x-2y+1
(a+1/2)²
=a^2+a+1/4