(y+1)(y²-y+1)+y(1+y)(1-y)
问题描述：
(y+1)(y²-y+1)+y(1+y)(1-y)
答
=(y+1)(y²-y+1+y-y²)
=y+1
(y+1)(y²-y+1)+y(1+y)(1-y)
=(y+1)(y²-y+1+y-y²)
=y+1