因式分解:(x+y)(x^2+xy+y^2)-xy(y-x) 3(x-1)^2-18(x-1)+27

问题描述:

因式分解:(x+y)(x^2+xy+y^2)-xy(y-x) 3(x-1)^2-18(x-1)+27
题目是(1)
(x+y)(x^2+xy+y^2)-xy(y-x)
(2)
3(x-1)^2-18(x-1)+27
不小心打错了

(x+y)(x^2+xy+y^2)-xy(y-x) =(x+y)(x^2+xy+y^2)+xy(x+y)=(x+y)(x^2+xy+y^2+xy)=(x+y)(x+y)^2=(x+y)^33(x-1)^2-18(x-1)+27=3[(x-1)^2-6(x-1)+9]=3[(x-1)-3]^2=3(x-4)^2