已知y+2x=1,求代数式(y+1)^2-(y^2-4x)^2

问题描述:

已知y+2x=1,求代数式(y+1)^2-(y^2-4x)^2
有个平方还真把我搞懵了.

2x=1-y带入
(y+1)^2-(y^2-2+2y)^2
=(y+1+y^2-2+2y)(y+1-y^2+2-2y)
=(y^2+3y-1)(-y^2-y+3)