-2x²(1+y²)是怎么等于-x²(1-y)²-x²(1+y)²的?
问题描述：
-2x²(1+y²)是怎么等于-x²(1-y)²-x²(1+y)²的?
答
-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...