-2x²(1+y²)是怎么等于-x²(1-y)²-x²(1+y)²的?

-2x²(1+y²)是怎么等于-x²(1-y)²-x²(1+y)²的?

-2x²(1+y²)
=-x²(2+2y²)
=-x²{(1+y²)+(1+y²)}
=-x²(1-2y+y²+1+2y+y²)
=-x²{(1-y)²+(1+y)² }
=-x²(1-y)²-x²(1+y)²
合肥荣业新材料设备有限公司回答

2(1+y²)
=1+y²+1+y²
=1-2y+y²+1+2y+y²
=(1-y)²+(1+y)²